The knife kept plunging deeper, too:
the rumor is, microsoft was in the market for first parties. they weren't looking to build their existing studios, but buy others outright. they bought bungie, tried to buy nintendo (and wound up with rare sometime later), and tried to buy sega. from what i can remember, sega backed out of the deal at the last minute, but were still contractually obliged to complete x amount of games for the platform. i wouldn't be surprised if peter moore was partially behind that move, especially considering the supposed animosity between sega usa and sega japan, and where peter moore went next (heading microsoft's japanese division).
so microsoft wound up with a bunch of exclusive sega games in long-running and popular series, and did jack shit to let the public know about them. sonic mega collection plus and nfl 2k3 were the only games on the xbox to sell over 300k copies in america.