It would seem that GPL3 has been out long enough that if its merits for switching the kernel to said license were so important it would've happened by now. Or is it possibly the case that not everyone has the exact same values as you and still enjoys the flexibility of using the kernel under GPL2. God forbid someone get rich off the collective works of society. Sure, they should contribute back, it's the nice thing to do, but really not everything has to be about forcing openness. I would rather a company build on a solid foundation rather than have to reinvent the wheel all the time. It tends to result in better products.
That's what phones are after all, consumer products. 99% of the world just wants a product and could give two shits about rooting or jailbreaking the device. The vast number of people who buy these phones will just be focused on comparing things like price, service, available apps and the usability of the product. There's a reason that the iPhone is/has been so successful. It came with a slick UI out of the box(and has gotten slicker). Sure it's not open, but most people don't care because it doesn't impact the way they want and expect to use said device. Sure, you're effectively renting the hardware since you can't run whatever you want on it. Sure, that's not ideal. But given the choice between a semi-locked down system that is easy to use, looks good and does what I want or an open system with a crufty UI and so-so ease of use, I'll take the first one most of the time. Especially if it's a device I don't want to have to mess with constantly.
Yes I've run Linux and Solaris and I like them for their purpose. I also run OSX on my macbook and windows7 cause they fit my purposes. I appreciate the openness of Linux and openSource, but I can also respect the decision not to be open source. And as I've spent more and more time using computers, the need for good UI design has become more and more a factor and I've come to care less and less about being able or needing to hack code to make it work.