xhonzi said:

Iron Man's mask when it's off- I blame Michael Keaton and Batman Returns. Ever since then, every masked character seems to spend 50% of their costume-on time with their masks off. The filmmakers are running out of ways to keep those masks on...

It's the other way around-filmmakers aren't running out of ways to keep the mask on, they are looking for ways to get that mask off. An actor has more range when you can see his face. Add to that I'm sure if they are paying an actor millions to play a part they don't want to cover up his face. The Toby Spider-man willfully took his mask off when he was trying to save that train in Spider-man 2-what the hell was that?! But then we could see all the effort and strain he put in trying to rescue those people.

Watch the commentary for Avengers-Joss even mentions the bank fight with the alien and Capt. America was just an opportunity to get his mask off. Hell, even in one of the trailers for Cap 2 he drops his mask on the ground before the big showdown.

It will be curious to see if Ben Affleck's Batman is able to keep his mask on.