Because I like to try different things.
Because I have been less than impressed with the factory setup on this phone. I am playing with launchers and swapping apps, but one thing keep nagging me about Android in general.
I feel like the entire phone is one giant walking advertisement.
I feel like every time I make a keystroke I am being data-mined by both Google and any/all third party apps that are installed, in addition to being innundated with advertisements on a majority of the apps.
This may not be the case at all; however, that is the current perception.
WP7 has been ported to other android devices, and upcoming Mango release has opened the doors further for hardware support.
That, and I like to tinker with things. Rooting is most likely my next step, but I shouldn't have to risk bricking my phone just to be satisfied with the OS.