The OEMs and carriers want to differentiate in SW too, not just in hardware. They don't want to be dumb pipes or just the "boxes" that android ships in. The

The OEMs and carriers want to differentiate in SW too, not just in hardware. They don't want to be dumb pipes or just the "boxes" that android ships in. They happen to suck at SW and screw up the android experience. Without the opportunity to mess with it, Android wouldn't be as attractive to them.