Halo did this for their story outside of the original game, and they're all pretty good (not Game of Thrones, but good). It helps fill in any story arcs not tied in and added depth to the game's lore. I would love to see this for Destiny! They have whole races to work with for backstory and honestly would help the Grimoire out. Hell, they could make that into its own book!
I'm not sure how many of you ACTUALLY spend time reading, but I think it would be fun to get more insight into all that the Destiny universe has to offer that we just don't know about outside of collecting ghosts and fragments.