Boob-shaped plate armor is NOT important or necessary.
One may argue that there should be a visual contrast between male and female, but when in plate armor it is not necessary to provide a visual cue. The lighter the clothing, the more visual differences will be. If your female and male characters are possessing equally hulking bodies which can fit plate armor...well there is no reason or necessity to feminize that armor. Your female is as bulky as your male after all (probably as ugly as a male). When they remove their armor the difference might be seen clearly.
Of course...if you prefer anime style skinny women with enormous strength and boob-plates...then by all means. As a male, I can say it can be quite attractive but in logic it fails miserably.
My point is, in a RPG, the gender differences should be used in optional solutions, side quests, body shape (which becomes similar for each gender under heavy garment, different with lighter garment), portraits, dialogues etc. Thus boob-shaped plate armor is simply overrated.
