My hypothesis is they want to prevent piracy of paid apps, under the flawed logic that non-phone devices are more hackable due to the lack of cell carrier meddling/stranglehold/rooting counter-measures. This kinda makes sense if you think about unlocked/non-carrier subsidized android phone in other nations, which also cannot access the market. Also, American cell phones these days are highly traceable. For example did you know if you call 911, the dispatcher instantly knows your full name, home address, and exact GPS coordinates, and that you can't hang up until he or she lets you or you rip out the battery? While they might ask your name and location anyway, they're really just trying hide this fact.

Back to the topic of working around this block, now that root access is easy on the eDGe, maybe we can make use of this: http://code.google.com/p/market-enabler/