“When to sessions of sweet silent thought…”
Sufferin’ Succotash, Shakespeare!
Eye contact. Acknowledgement of each other’s presence.
A movie is just a recording. It’s like a voicemail. It’s a pre-planned production that never changes. A live performance, however, acknowledges that an audience exists and responds to it. It doesn’t have to be anything so overt as conversing with the audience, but the performer can pick up on audience moods and reactions and incorporate those into the performance. Energy feeds on energy and becomes a positive cycle that makes it something of a shared experience. Ever watch a comedy movie where the whole audience laughed in all the right spots? There’s a connection to the rest of the audience there, and in a comedy play there’s a connection to the performers as well.
This is less true in large-scale productions, where the audience is just too big and too hidden behind lights, but in intimate settings where the audience is gathered around a relatively small stage, you can really feel it. I personally love comedy, and a comedic play has more depth and enjoyment in it than a comedic movie, especially when there’s a little fourth-wall bending.
I was going to compare live theatre to live music as well, but as you’ve never heard any live music either…*
Watching a good play can produce a very intense, physical visceral reaction. The actors create an atmosphere that draws the audience in, makes you sweat and your heart pound as they sweep you along with them. I love cinema as well, but have never had that reaction so intensely even with the best films. I think it’s something to do with you being physically present, so you’re almost involved in the action yourself Also the fact that it can all go wrong is kind of exciting, like watching someone walk a tight rope without a safety net.
Last summer I saw Kevin Spacey in Richard III at the Old Vic and came out feeling not just emotionally wrung out but physically drained just from watching his performance. A loud and lively performance of As You Like It left me feeling slightly high and buzzy just from the sheer energy of the performances.
Unlike pizza, bad theatre is just bad. But good theatre stirs your soul.
Intimacy: When a live actor is acting, s/he can adjust his/her performance (and henceforth I’m going to use feminine pronouns, just 'cause I can, but all the following applies just as much to men, ok?) as she sees how it’s working for this audience, for this night. Different actors do this to different degrees, of course. And it also depends on the show and the director. Good actors in comedies are much more free to change things up - even changing lines, sometimes, if they suddenly think of a line their audience might think funnier. Have a young crowd tonight? Maybe that Elvis joke wouldn’t work as well as a Justin Beiber joke. Have an older crowd tonight? Maybe changing it to a Milton Berle joke would make it funnier.
Often the changes are more subtle than that. A longer or shorter pause for laughter. A shoulder shrug or slight wave of the fingers to acknowledge spontaneous applause. A nod of the head and quirk of the eyebrow to acknowledge the one single guy who got the joke and laughed out loud (which often clues in the rest of the audience that there was a joke there, and then they get it.)
Actors in live theater often make eye contact with members of the audience. This is called “breaking the fourth wall,” and it can really draw an audience member’s interest. It can be threatening, even, in a good way, making you realize that the theme or message of the scene has meaning to YOU. (Example: a monologue about why young people should vote has a greater impact if the actor catches the eye of some young people as she’s speaking.)
Every audience is different, too, not just every production. One audience may laugh more, or cry more. Some audiences clap between songs and some don’t. Each choice by the AUDIENCE changes the flow and energy of a show, just as much as each choice by the actors. Even when an audience is silent, there are different kinds of silence, and the actors feel it, and respond to it. Rapt silence and bored silence sound and feel completely different. A bad audience can break a show just as quickly as a bad actor.
Most actors don’t yell all their lines, by the way. Even high school productions can afford microphones these days, and professional theater has a wireless microphone hidden in the hair or set on the forehead or cheekbone, generally for every actor. That part I’m not so crazy about, to be honest. I miss the days when actors knew how to project. Amplified voices don’t have the same warmth and intimacy to me.
Sometimes “mistakes” or unexpected events make a show great. I remember one production of The 25th Annual Putnam County Spelling Bee where they pulled some audience members up to play characters in a spelling bee. The idea was to give the actors words they knew, of course, and the audience members difficult words that they’d mess up and therefore be “out” and get off the stage. Except they happened to pull up a REALLY good speller. I remember she spelled **accommodate **correctly. And then bureaucratic. And then an actor whispered something to the actor giving the words, and he came up with sesquipedalian, and she got that right! The audience was laughing, of course, and the actors were laughing, and we all wanted to see how they’d get out of this and move on with the show! The actor giving the words thought about it for a moment, and then gave her the word… “W-E-A-T-H-E-R…” she said, and he rang the buzzer and jumped up and said, “NO! 'Whether! Whether or not you spelled it right, you’re wrong!” And the audience lost it. He’d “gotten” her with a homophone!
Okay, maybe you had to be there. Trust me, it was hilarious when it happened. It was hilarious because it was unplanned, and unwritten. And that kind of serendipity is impossible in the movies.
I really love live theater, can you tell? I would, without any snark or judgement, suggest that you give it a try. It’s a totally different thing from movies - not better, not worse, just different. Give it a try and see if it moves you. You may be pleasantly surprised, or it may not be your thing. That’s cool, too.
ETA: Oh, yeah, and bad theater is just bad, I agree. If you’re not enjoying yourself at the intermission, just leave. It may not be bad because you don’t like theater, it may just be bad. I’ve walked out of a few shows in my day.
And on a technological note, live theatre was using 3D long before movies ever tried it.
Just to add on the back of WhyNot’s post, that sense of emotional connection does work both ways - as an actor you can sense how the audience are reacting. Not just whether they’re enjoying it or not, but how. Whether it’s light-hearted, laughing crowd, a more cerebral, thoughtful one, or a challenging, almost aggressive one you have to work to win over, you can sort of sense it after a few moments on stage and your performance adjusts accordingly, often without you realising it.
Many theaters have started having at least one night of their show’s run be a Pay What You Can Night whether that’s 50 cents or 50 dollars. The biggest hurdle is getting someone who’s never seen a play to go to the theater. Once someone sees a play for the first time, they’re a lot more amenable to seeing other ones.
When the recent film version of The Woman in Black came out, I immediately thought that the ending must either be different from or much less effective than that of the play. I haven’t seen the movie so I don’t know how it ends, but I feel like the ending of the play needs to be seen live to really work.
I’m going to be vague even in the spoiler boxes because it would take a long time to fully explain this, but the plot involves a ghost. Anyone who sees the ghost is cursed. By the end of the play, the audience has seen the ghost appear in the theater. I can’t imagine that seeing a ghost onscreen would have the same effect. Either way the audience of course knows that it isn’t a real ghost, but in the theater you have at least seen the “ghost” physically manifest itself just a few yards away, which seems scarier to me than seeing a picture of the “ghost” that was taken elsewhere projected onto a screen.
When we were teenagers, one of my siblings was active in a community theater group that did all original plays. One of their productions was about the life of sex researcher Alfred Kinsey, and the entire cast wore clown costumes. There were no sets or even furniture onstage – the bodies of other cast members were used as tables, chairs, etc., when necessary.
I was not terribly impressed by this play, but it sure was different from anything I’ve ever seen in a movie.
ETA:
I believe pulling people from the audience is part of every production of this play. I saw it on Broadway and ALMOST got to be one of the extra spellers. 
This.
I am admittedly quite biased on the matter, as most of my favorite plays tend towards the nonrealistic and highly theatrical mode, but I can’t imagine a lot of plays being done anywhere but a theatre, even with some hefty revision for a screenplay adaptation. Cinematic convention and theatrical convention aren’t the same thing. What’s believable on stage can be clunky and awkward on screen and vice-versa. I would also note that plenty of contemporary playwrights work both in the theatre and in film or television, which suggests to me that writers will choose what medium works best for what they’re trying to achieve with a given piece.
But anyway, I would definitely, definitely look into finding some local theatre if you can, like everyone else has suggested. I minored in theatre in college and friends from then are forever organising small, inexpensive productions in that not-terribly-large city where the college is. Even the nearby regional theatre, which is a nice professional outfit in a small town in the middle of nowhere, tries hard to get the community involved with discounted tickets, etc. I’m guilty of continuing to be the world’s worst theatre student by never going to any of these, but when I’m in town with some spare cash, I do try to go to productions that look interesting. It’s not really an experience that can be explained just in words.
Film removes some limitations, but imposes others. There is a lack of authenticy with film I’m always aware of (how many takes did that shot take). It takes a lot of talent to be able to emote on stage - projecting your lines without shouting - acting on film takes a different set of talents, to be subtle…not all film actors can act on stage, not all stage actors can transition to film.
But a simple answer to your question, theatre still exists because people want to both do it and see it. Shows sell out. Or they fall flat and close. People in small towns in the middle of Iowa start community theatres so that the town dentist can play the Alan Alda role in Same Time Next Year and the community buys tickets because they enjoy going. Then, when they go to New York on vacation, they spend hundreds going to a Broadway show, because its enjoyable.
Me, too–I was never miked, in big theaters or small–we knew how to project back then (and no, I was not on the stage the night Lincoln was shot, no matter what you may have heard).
And true too about playing to the audience: “How can you do the same play night after night?” my mother asked me once. “Isn’t it boring?” But it is–or should be!–a *different *play every night, and different audiences reacted very differently to the same lines–you adjust to them, and feel them out (in a polite, ladylike way, I mean).
I have seen films of Liza Minnelli and Marlene Dietrich and Ute Lemper performing. And I have seen all of them in person onstage–breath-taking, heart-stopping, all of them. No comparison to seeing them on film.
I came in to post this…almost word for word.
These darn kids with their long music & loud hair!
Growing up in the 1970s I was fortunate enough to see several classic Broadway shows, Beatlemania, Pippin,* A Chorus Line*, even got to see one of Yul Brenner’s final The King & I performances (he was phenomenal!) Only a few years ago a finally bought and watched the DVD production of Cats and really wished I’d gotten to see that live.
As everyone’s said seeing a film and seeing a play are two totally different things. Even more different than seeing a band play live. There is something indescribably visceral about seeing real live people up on a stage in front of you, playing make-believe. If you’ve never been to one it will take a few minutes just for it to sink in that, yes, that is indeed what is happening. But then you’ll quickly find yourself completely immersed in it. It is absolutely something you should experience.
One important thing about it that I always like to remember: Until only a few generations ago, for all the rest of human history live theater (and music) was the only form of entertainment. When Wilkes Booth killed Lincoln he was the most famous actor in America. It would literally be like having Tom Cruise shoot the President right on the red carpet today…
I agree with everything that’s been said.
I’d add that modern theatre is the place for experimentation. There’s a lot of very create, edgy work done in theatre.
Movies are all about making money. The best Theatre is art.
NOOOOooooo! I feel your pain. Truly. One of the best nights of my life was when I got pulled up for a production of Too Much Light Makes the Baby Go Blind at the Neo-Futurists. There was one of those random, spontaneously generated running gags that cropped up that night of everyone yelling, “Take off your shirt!” at an actor during tense moments in the scenes. Some of the male actors actually did take off their shirts. The chicks kept them on, naturally, which only encouraged the guys (and lesbians, I presume) in the audience to try harder.
I was so proud of myself when, during the middle of the scene I was drafted for (which I don’t recall a thing about), a wag from the audience yelled, “Take off your shirt!” at me. And I DID! (I’m a chick. With a very large rack. I did have a bra on.)
Proudest audience participation ever. I got the only standing ovation of the night. Threw off their very tightly scheduled show by almost 5 minutes. Two of the professional actors started laughing so hard they had to leave the stage. I felt like Robin fucking Williams. 
That’s the power of live theater, son. I’ve never been so caught up in a movie that I’ve whipped my shirt off in public. 
Better acting and better dialog. You also are required to think and use your imagination. You can’t do a car chase, so the theatre would improvise and you’d have to pretend or the dialog would have to be rewritten to require the actors to speak and conjure up in the audience’s mind the action.
There’s nothing wrong with either and they both have places and they both have good and bad actors, set designers and directors.
I like your ideas–you have something here I haven’t considered before.
Okay, I don’t know what kind of movies you prefer, but I’ve seen plenty that are art.
Theatre is the gateway for the vast majority of actors on TV, film, and elsewhere. It can be performed by amateurs and started young. It trains actors in all sorts of important skills in the industry - singing, dancing, speech, and of course acting itself.
Most of the answers so far have focused on what live theater offers the audience, which is all right and proper, but it may be worth pointing out that live theater offers the actors (and other people involved in putting on a performance) plenty of things that cinema doesn’t, and that one major answer to the thread title’s question is “Because people want to put on plays.”