There are things however that customize your look but you can not use in the game. The example was a knife (some kind of a knife) that you carry but you can't use. It is used only to serve the visual purpose of your character. I wish it was used... LOL
I don't know a lot about the technical stuff, but I'm assuming that having to keep track of who is wearing what and using what suit upgrades would take up some power. --- I apologize for whatever I just said.
I read an article saying the Suit Upgrades will act as Perks and saying that the Suit Upgrades will change the characters appearance as well as having its own ability like Stealth which makes you not appear on radar