I think they left Microsoft because they wanted to make games at their own pace (they must have crunched like crazy to get Halo 1, 2 and 3 out the door), own th

I think they left Microsoft because they wanted to make games at their own pace (they must have crunched like crazy to get Halo 1, 2 and 3 out the door), own the games they create, and reach as broad a customer base as possible (i.e. releasing their games on multiple platforms). Infinity Ward is fully owned by Activision (and so are their IPs), so their situation is different.