There is fragmentation, but is that the fault of the OS or the manufacturers, or the carriers? Google writes the OS. But the manufacturers take it, customize it, toss it on dozens of phones that are all designed to be obsolete in 6-12 months max, and then the carriers make demands on what they want on it, what can't go on it, etc...
Google just writes the OS, but when it is given away for free, you cannot make demands and mandates on how it is deployed.
If Apple released iOS to a host of manufacturers for free, it would be the same thing with the same fragmentation.
The way that they need to spin this, is that:
"Fragmentation means choice. Choice in manufacturer. Choice in hardware. Choice in features. Choice in form factor. Choice in size and even choice in price point. It is why Ford and GM offer many models of cars from the Aveo to the Corvette ZR1, from the Festiva to the Shelby Mustang and Ford GT. Android offers a phone to fit anyone's needs or budget. If you want no fragmentation, there is an option for you and it's called Apple. Your choices as a consumer, are white bezel of black bezel. Enjoy."