Guys, seriously.

"Why is the same armor more revealing for female characters?" should not even be a serious question.

The answer is simply "fanservice". Guys LIKE seeing scantily clad catgirls. It's as simple as that. Call it sexist or whatever, I don't care - but yeah, generally speaking male humans are way more visual than females, and this means that they are more vulnerable to tits and butts and legs and necks (yes, necks - Japan loves sexy necks).

This is all there is to it. I, for one, rolled a Miqo'te because of nekomimi and general cuteness. Having her resembling Gimli is not exactly what I would like.

So yes, more cleavage, more panty shots, more absolute territory, and more necks. Thanks.