So dispite any odd justifications you might hear were people say 'it is so people can identify why exotic your using' it is more to do with the fact that they can market ornaments for real money. Bungies developers have commented they like the fact that some times you can identify a characters build by what exotic armor and weapon they are using. The problem is that in this day and age of the game builds tend to center more around the subclass and aspects rather then an exotic. If this is the self justification they are sort of feeding themselves to keep exotic weapons from getting shaders and exotic armor from being mogable then well... they are lying to themselves. It is just them trying to pretend they are not doing it to help promote reoccuring monetization. In short Sony wants Bungie to make lots of money. Bungie wants to stay in business. So bungie dose a handful of dumb and lazy restrictions on cosmetics to try and promote microtransactions The most ironic part is I have decided against buying there armor sets off the store because I can never wear the whole set on a day to day basis. Thr N7 armor clashes with my exotics so I won't buy it.