Superman had underwater and space armor in JLU and his own show because I think they were going under the Post-Crisis idea of the time in which Superman could only hold his breath for a really long time (like a few weeks) rather than actually breathing in space or underwater. Thus, he needed some sort of breather to talk or in case he was hit too hard. And one may as well wear a whole new suit if one is going to do that.
I just wondered why Superman never kept his lead Anti-Kryptonite suit handy during his JL tenure.
At any rate, it does look like Kang's minions will be from across time periods:
http://marvel.com/images/gallery/story/15042/brian_reed_writes_the_avengers_emh/image/854507
The armor is weird, but, yes, Thor can breath in space because he's a god, but Hulk and no one else can. The Hulk's body won't turn inside out in space like everyone else's. As for why Thor would wear armor...he's a warrior. They like armor.
Armored suits are usually just an excuse for more toy variations, but I figure it will be part of Iron Man's "anti-Kang" gear. And they have already worn "anti-gamma" suits.
The only downside to them all being the same color is telling people apart in hectic fight scenes. "Is that Cap or Clint. Oh, wait, arrows, Clint." But we'll see. I'm curious to where things will stand with Kang and Ultron and even the upcoming alien threat when all is said and done.
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