To be honest I think destiny should add in trading. It would make the game more fun if people were able to trade weapons that they didn't need or want, you could also use it to help out a lower level friend, this honestly seems like a cool idea and I think the creators of destiny should really consider it.
-
Its been discussed to death but one of the main problems that trading would bring is what's happening to Blacksmith shader codes. 100 bucks a pop for a Gjally or Mythoclast. It would be nice to trade around gear to friends (either they have gear you want or vice versa) or to help out a lower level buddy but unfortunately it'd mostly turn into selling stuff for real money. Plus people are already pissy that players can simply buy exotic gear via Xur (ruining the fact its makes them not rare ergo not exotic and the "I earned my *exotic*" spiel).