Not having first parties for MS is a good thing, they specialize in building software and APIs. It's a better idea to lay a good foundation and let the third parties be an independent the creative force, rather than trying to purchase a large portfolio of studios and telling them what to do. MS is far superior to Sony on the developer side, which is why outside of Sony's first parties most companies choose MS as the lead console (superior tools, DirectX/XNA, better online integration/support).
The only downside is it leaves studios free to go multiplat, but given that their strategy has shown almost all multiplats to be superior on the 360 in performance and sales, it's paid off pretty well.







