There is a tug-of-war between creating a good social gaming experience and a good narrative experience. If you're watching slick cutscenes or listening to audio logs, you can't be BSing with buddies in chat. For example, I would consider a game like Bioshock to be an awful co-op experience. Other MMO games have quests like "bring me 10 wolf tails" not because they're narratively bankrupt, but because that style of quest design fits when playing with others - it's a simple objective that can take a back seat to the player's focus on social interaction. Did Bungie succeed with this approach? The community seems to not think so, by and large. I see them changing the approach in the future.