I think one of the advantages of that structure is the head of Google now just focuses on Google instead of trying to think about a dozen other businesses as well.
Indeed, focus is a great thing. Although weirdly enough, Android is still part of Google as well; you'd think that'd be a prime candidate to move alongside Google as its own venture.
The idea may be that android benefits a lot more from integration with other google products. Although I'm not sure on how inter-alphabet cooperation is going.
