Were they ever in fashion? Of course there’s always been the occasional person like your classmate who wears one, but I can’t think of a time where large numbers of men wore colored suits.
There were times when a large number of young men did. Check out tuxedo rental catalogs in the seventies.
Everyday men’s suits are only de rigueur in a handful of occupations these days and those occupations are in the most culturally conservative industries, so muted colors are to be expected. Everybody else might own one suit which has to be appropriate for any occasion and one of those occasions might be a funeral or an interview at one of those conservative companies. That one suit isn’t going to be anything colorful.
I wouldn’t say “everybody else” but “most others” do because they feel their sober suit will be needed for things like funerals, or the rare formal dinner. If you can only afford, and only want, one suit, sober makes a lot of sense. If needed, you can get wild with socks and ties. But if you are a fashionista who can afford to be daring once and a while, that rule does not apply. For most of us, fashion does not apply. But it sure can be fun.
gentlemen, let’s not forget about the second half of 1980ies …
And ISTM it’s really the core reason for the apparent demise of the colorful suit in the West. With “business casual” having taken over, for many people the full suit is moved into the role of either a sort of duty uniform (you are a lawyer or banker) or a ceremonial vestment (funeral, wedding) and you go for the style and color that you can make the most use of: sober and dark.
Yet 70s and 80s fashion is known for inspiring a polarizing backlash being still felt today for some reason. Really, WTH was wrong with pastels?
In any case the trend in our time is either go completely casual or go staid dark conservative and there’s no inbetween. Hell, as late as the early 2010s a POTUS could not even wear a perfectly good summer beige suit to an official appearance w/o the haters acting up.
Though let’s be frank, for many of us it’s just much much safer to go for the sober style. To literally be the grey man. It takes a high level of verve, of élan, of swagger, to be showy and call attention BUT at the same time not look ridiculous, and some of us just don’t have it.
All I care is that they get rid of the “left over from your grade 8 graduation” sizing system for men’s suits.
Zoot suits were popular among a certain segment of the population (mostly, but not exclusively, young black men) in the 1930s and 1940s, and often came in brighter colours.
I’m not sure if it was the pastels, but I suspect that cheap polyester that you either roasted or froze in played a big roll. Manmade fabrics tend to “breathe” better these days. To be fair, we did laugh at the ruffled, pastel edged shirts.
I’m not sure the full sherwani suit could ever become anything but a major-special-occasion garment, but perhaps we should set our sights on cultural-appropriating the Jodhpuri jacket. Silhouette similar to a traditional western business suit, but much more interesting range of fabrics (bonus: no necktie required!).
Really. All study reports and simple evidence of our eyes say most of us are NOT “slim fit” and actually moving in the opposite direction by the day 
Realistic sizing, please…
( I get it, the idea is you buy a suit to fit you at the hardest to fit point, and then take it to have the rest altered.)
And also especially Latinos
I remember being puzzled that the dress code for my school orchestra (c. mid-late 1990s) always specified a “dark suit”…”what, there’s another kind?”
I myself am a Dutch-Scottish white fella and my friend is/was (we lost touch) Puerto Rican, so the suit may not have been as unusual for him as it was for the Littlest Rhombus.
If only I were still of the age that I was going to Prom.
I may, ahem, have one in the far corner of the closet (that someone picked up for me on both clearance & employee discount) but they’re like ugly Xmas sweaters. I own one of those that I wear, what, twice a year? I can’t justify wasting money (& closet space) on something that’ll get worn so infrequently.
I think this is likely a big factor. In the 1970s, we had the rise of the “leisure suit” in the US, which would seem to be a contradiction in terms, but they were meant to be worn primarily for casual occasions (parties, going out, etc.), and were much more flamboyant.
I’ve also come to discover, in the last few decades, that a lot of men now don’t even own a single suit. A few years ago, we were getting ready to attend the funeral of the mother of one of my best friends from college, which was being held in the small town in central Wisconsin where she lived. My wife asked me, “what are you going to wear?” I said, “a suit, of course, it’s a funeral. But other than Brad (my friend’s brother), who always dresses well, I will bet you that there will not be another guy in a suit, and there’ll be at least a few people wearing things with Packers logos on them.”
I was 100% correct in my predictions. I will bet you that most of the men who attended that hadn’t owned a suit in years.
I think “they” have done a pretty good job getting young males to care about fashion and hygiene lo the past dozen years. Have you not seen the toiled-over facial hair?
Colorful clothing will undoubtedly reappear.
My son wore a colorful suit for his wedding, but I expect that was a one-time thing, since it looked something like this.
Yeah, I hadn’t bought a new suit since, maybe the 90s, until a couple years ago when I realized my uncles and aunts were all getting…of “that age.” I figured I’ll probably have a funeral or two per year for the next decade or so, so I bought a new one. The two funerals I’ve been to since I bought it, I think I was the only guy wearing one, and now I kinda regret buying it.
And don’t forget the ones who do own a suit that hasn’t fit in years. My husband stopped wearing a suit to work every day about 30 years ago. Kept them anyway, all of them. Wore one occasionally for a funeral or wedding. In 2017, my daughter got married. Luckily, I told him to check a few weeks before the wedding because of course none of them fit. I think he bought three - a black one for funerals, because “dark” isn’t good enough and two more for weddings. One funeral and two more weddings since he bought them - by the time he needs one again , they either won’t fit or will be out of style.
I think men’s suits are conservative enough that they really don’t go out style much.