“Necessarily” better? Of course not.
Mere length is not always a virtue. That’s always been true, whether we’re talking about movies, songs, novels, plays, poems, operas, or almost any other art form.
But it isn’t necessarily a drawback, either. It all depends on how interesting the story, characters and/or themes are, and how talented the creator is.
“Anna Karenina” and “The Brothers Karamazov” were both over 800 pages, but for me, they flew by. I was so engrossed, I finished them both quickly. On the other hand, I’ve read short stories that seemed to go on forever (like Melville’s “Bartleby the Scrivener”).
If a movie is gripping, 3 hours elapse in the blink of an eye. If it’s a bore, 90 minutes seems like an eternity.
Length is only a drawback in a bad piece of work. I mean, both King Crimson and the Ramones have recorded a LOT of lousy songs over the years… but the Ramones’ bad songs are over in 2 minutes, while King Crimson’s bad songs may last 15 minutes. On the other hand, Mozart’s “Jupiter” symphony lasts 40 minutes, and nobody think’s it’s too long.
So, there’s no hard and fast rule. If you’re a writer, and you think you’ve got a great story, and you think you need 600 pages to tell it properly, by all means write 600 pages. If you’re a composer, and you think the song you’re writing needs 12 minutes, then write a 12 minute song. But do it because you think the work calls for it, not to impress people.