But, sure lets go with that.
Quiet is a Sniper who has to wear as little clothing as possible. Nylon is certainly an interesting solution but she intentionally poked holes in it pretty much ruining the point of it. She doesn't wear any padding for her knees or elbows or ass and her boots aren't properly done up. The only thing she has going for her is she has the forethought to tie her hair back.
All the while she presents like she was part cat (something I honestly thought would be the twist a few times. That she had cat DNA injected into her).
Now... here is Christie from Tekken
She is a fighter of a form of Dance Martial arts so she wears brightly colored and flashy clothing, she wears quite a bit of sexualized clothing but it fits her.
On her hands are protective gloves and her knees are properly covered. She even tied her hair back.
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Christie's Clothes = Christie + Her personality
Quiet's Clothes = Male Fantasy - Her Personality - Quiet
Or to sum up...
I do NOT believe Quiet would be wearing what she is wearing if she had any sort of autonomy. Add in that her alternate costumes aren't ways to possibly put more clothes on her or make her less conspicuous but are rather ways to show off her bod even more. Did she sow her leather diaper herself or was it standard issue?
Now Christie? Yeah I could believe she chose to dress herself that way. and Christie is the worst example I could have given (she WAS added for fan service)