30 years ago, we had absolutely no problem whatsoever going to see a movie whose lead character was dressed head-to-toe in colorful spandex.
Here's where the argument falls apart. With pretty much the sole exception of Superman: The Movie, superheroes were seen as either jokes, for kids, or at best guilty pleasures. It wasn't until Batman '89 that they started becoming cool and it was mostly due to its dark and gritty look.
While the traditional spandex and bright colours can work for more light-hearted heroes like Spider-Man or Superman, it can't be on badasses without the audience revolting. Nobody would ever take Wolverine seriously if he was wearing yellow and blue spandex.