I kinda disagree that it's useless. Addon-side info is a solved thing. Just knowing if a quest has been completed or not has been missing. Blizz provides the missing pieces, and quite an array of addons will benefit, for example loremaster supporting addons, tourguide, questhistory etc etc. You can now query if others in the party have done any old quest not just the ones you can share. Pretty good addition really.