Certainly. However if hundreds of millions of dollars and my job were at stake, I could see why movie execs would be risk averse.
No, I think it's entirely legacy reasons. Superhero costumes since 1980 tend to be far less garish, because they can be.
But once again, bright costumes make more sense in print than in live action movies. I think Reeve's Superman is the closest we ever got to making that work, but as I pointed out earlier, that was over three decades ago and tastes have changed.