It's really weird and interesting seeing him be considered like this and seeing Joe Staten be involved even just with a novel, since they both said when Bungie split they really wanted to do something other than Halo. I wonder what could change someone's mind like that. Money is the obvious thing but I'm sure there are other means of getting, if not the same amount of money at least close to it, and there's artistic integrity and lack of inspiration and sheer boredom to take into account, for and against-- what if Joe found he couldn't come up with good ideas for other things? I'd love to hear how it happened some time.
As for music, I think they could coast for another game or two at least on variations of what Marty did (though I'm not saying they should), it stands up to repetition that well.