Being totally fair, it was this way also in SoulCalibur IV. Only the main characters wearing their default outfits would behave as you describe, with battle damage. If you used Amy's outfit on a custom character or on another character it would behave just as it does in this game with regards to breaking.I noticed recently since my brother has just been doing a completion run on SC4 that they didn't add the broken variant of Amy's SC4 costume which is a little disappointing in a sense if that's what it means for other characters old outfits going forward. Especially since we can't disable armour breaks.
I hope armour break disabled option becomes a thing in the future, I really do. Sick of playing Amy and her feet spontaneously showing themselves. Not like SC4 where her leggings got torn up and her boots too, I'd rather it just doesn't break.