I feel like I didn't know anything about Destiny prior to Taken King. I've been playing since the beta and I feel like I really understand the backstory now. Pretty sure when Bungie saw people upset about the grimoire being outside the game and people having questions, they made more cutscenes and really explained the story by the time Taken King came out. Hopefully they continue with this way of story telling in the game, move the story forward, and explain the history with RoI gameplay.