Sometime a player change traits trying to test new builds or, for instance, for supporting a team in a dungeon. So it could be’ a nice idea allowing players in WvW to change abilities, depending on the activity they choose i.e. support repairing or building sieges… Maybe we’ll see an Abilities Master that provide changes for a few silvers?
Upgrading is very expensive and it would be’ a nice idea rewarding ppl that use their money for support the hole world: zerg is funny but When u come back to a keep waypt and u see a red shield it means that somebody spent his money for support u :-)