Armor looks are tied to teh type of of armor that you are wearing. And Armor is a type of equipment that you are using. I think it would look out of place to allow too much player's to customized armor. I think its enough that player can customize their costumes.
I've always been a huge fanatic of having unlimited customization of costumes in games like City of Heroes and Champions Online. But I'd have to agree that we don't really need that here for armor.
Different kinds of armor look the way they do because of the types of features they provide. As a piece of tech it doesn't really make sense that an armor that provides benefit X could actually look radically different from another armor that provides the same benefit. We have pretty flexible customization options for our uniforms already. We don't really need people running around with mismatched multi-colored armors with sparkly tassels or whatever.