Metal Gear Solid has never been a franchise that's lacked fan service when it comes to depicting attractive characters, but that doesn't mean the characters don't have a reason for looking the way they do.
Last week, Hideo Kojima tweeted that he was making some of the characters in Metal Gear Solid V more erotic as a means of inspiring cosplayers and to also boost figurine sales. The reaction to that idea was not entirely favorable, particularly when it came to a sniper called "Quiet." Later, he clarified that maybe "erotic" was the wrong word for the character designs, and also claimed that the narrative themes of the game lined up with the reaction that people had to the sexy sniper. Ultimately said sniper has a reason for looking the way that she did, Kojima asserted. He also stipulated that her design was some sort of antithesis of the average, over-exposed female fighting game character.
The Camo Theory
Although his reasoning came off as unclear—unsurprisingly, since we can't actually play the game yet to tell what he's going on about, or whether he's successful with what he intends—fans have already taken to hatching theories about Quiet's appearance. The GIF you see above is key. Notice the Rorschach-like marks on her face, which seem to disappear? What could they be? According to an image floating around the internet, it's camo, and it explains why she's so scantily-clad.
Now, this theory isn't being outright accepted by everyone or anything. Some of my Metal Gearhead friends seem skeptical because the camo in question isn't introduced until 2014 in the games (nevermind the general cynicism about the likelihood of a mute sexualized character actually ending up as a 'strong female character'). It's possible it's an early version of the camo or something, if not another type of camo altogether. Or maybe it's not camo at all, who knows! But it doesn't seem too far-fetched for it to be camo, right?
The Torture Theory
Another intriguing theory, posed by Whorses, is that she's actually dressed the way she is, not because she chooses to dress that way, but because that's what she looks like post-torture. Recall the first time she was introduced to us? If not, watch the start of this extended trailer here, where you can see her being electrocuted:
In that context, Kojima's tweet about people likely feeling "ashamed" of their words and deeds after we realize the reason for Quiet's appearance makes sense, no? And it would explain why some of her clothes are torn up. ...but then again, there's another character that gets tortured in that trailer who seems to be fully clothed, so who knows. Maybe the idea that she gets stripped down for/because of torture doesn't hold water.
In a way, whether or not the theory is correct isn't the point with these things, if you ask me. Theories are just fun to muse about. It's kind of like the New Coke Theory, which stipulates that David Hayter, the original voice actor for Snake, is being replaced by Kiefer Sutherland as a roundabout way to trigger fan's nostalgia for the old Snake. The idea is that eventually, old Snake will come back, triggering better sales for the game.