Microsoft's publisher-friendly practices and their aggressive move to court big money (CoD DLC, CoD itself, the NFL, EA/Acti friendliness) and their decision to basically continue as is for indies all suggest to me that they're very down with the current AAA-centric model. You don't break profit records with indie games-- you break them with your annual CoD release, release-parties, advertising money, tie-in money, and that sort of thing. You're right that the big pubs are responsible too, but Microsoft absolutely supports that model (where do we think the recently 180-d DRM choices came from? It was (if you ask me) a clear attempt to cozy up to big pubs).
I don't like it, but it's absolutely where the big money is, and I think that's exactly what Microsoft courts.