Right now, XP is only used for the cash shop. If you (Bungie) could bring back the system where nodes on a weapon or armor piece could only be unlocked after gaining a certain amount of XP with that item equipped, not only would XP be useful again but we would have something to grind for! You could treat all of our current items as new/unupgraded for the purposes of implementing an update. To be quite honest, I’m not suprised I don’t see more people talking about this. We would have to work for our weapons again if this system was brought back.