I feel the need to point out that as far as costume insanity goes the armor is much worse
you can make a decent argument for Rinka being so unprotected because she specifically chose to be for mobility reasons or whatever (even if a few more layers wouldn't hurt) and in general she seems to be designed to give off the look of someone that's more used to a primitive lifestyle, which the design overall accomplishes
now, onto armor
heavy, metal, surprisingly flexible, expensive, "I ain't dying today" armor
It's actually not particularly stupid to decrease the strain it would have on your torso to give particularly large breasts some room to not be squished forever (disregarding the flexibility issues and whatnot and how if she has the muscles to deal with wearing half of that all day I don't know how the hell all that fat is staying there)
it is COMPLETELY STUPID to make it simulate bare cleavage (this thing is supposed to COVER YOU)
there is NO AESTHETIC THAT IT CONTRIBUTES TO other than making the wearer, and the designer, seem pornographic
I don't know who invented this idea but they need to die if they haven't already. It's even dumber than the muscle-armors ancient Greeks liked.