I suspect it comes back to Job's strategy for the Mac back in 2001 (I think it was 2001, not sure). He talked about how computers had gone through several generations, and that we were moving into an era where the PC/Mac was the "digital hub" that kept all your devices in sync and playing nicely with each other. Google would probably argue that that's the responsibility of their servers.

With the iPhone and iPad doing as well as they are, I imagine conversations are being had at Apple about what the future of the Mac really is. Even if it has much of a future at all.