I agree with most of what you say, except for this last part:
"What Google wants is to squeeze as much power/influence as the can over what they can put on the OS/Web Browser. "
I think it is even simpler. Google wants more devices to access the web and MS does not actually do a very good job at that.
MS (and most cell phone manufacturers) prevent the creation of cheaper low end web devices, google sees this gap and wants someone (they don't care who) to fill it. They see that since there is a device gap, they are losing potential customers. The faster they can fill this potential burgeoning device gap, the better...