Honestly? I really don't know. Maybe because Microsoft isn't seen as a "cool" company whereas Sony, Apple and Samsung are seen as cool.

WP7 is a weird, and a very hard sale that's not being sold anywhere in massive numbers. It's an oddball OS that people think looks childish at first. And it's too closely related to the failed Zune... which, while I loved mine, people shunned it for the simpler, more liable to break iPod.

And no... I think slapping a Nokia label on it will not bolster WP7 sales. In fact, in the US, Nokia has been relegated to those cheap flip phones that grandmas still like. Nokia's presence in North America is sorely lacking and spiraled into a depressing mess. I don't see Nokia needing WP7 as much as WP7 needs Nokia.

But that's my opinion. Take it with a grain of salt.