Hrm, interesting. My main experience with boob-flattening are corsets and bulletproof vests. Both are quite uncomfortable, don't get me wrong. My main issue is making super exaggerated shapes in the armor to accommodate breasts or to just say, "hey, look. boobies." Keep in mind, male armor isn't just flat. There is some sort of curve for certain kinds of chest armor, so it's convex instead of concave, for reasons stated in the OP about protection.