Funny that you mention WoW as an example, considering Blizzard helped mentor Bungie in the early days of destiny 1 and they told Bungie player trading was one of the worst decisions they ever made and suggested not adding it to the game, at the time Bungie had added the option to menus as a filler, which you can see in the early alpha videos but it never actually went anywhere. These days though it'll never happen for the simple fact it would be lost income, all those private trades for real money that will happen from day 1, they already ban for recovs because its money they dont get a part of you really think they will add trading.