The iron banner is a half assed "event" if its the only thing bungie does as a limited time event too, it might as well leave it as a permanent mode along with the queens wrath (With updated gear) since it can certainly fit in the tower and the game has so little to do most of the time. A little variety and content is always welcome. (Even if it doesn't really add content just a diferent excuse to grind the same missions on the same planets as the rest of the game)