Well, I'd say they've sold well for a number of reasons:
-They came in at an initial price point way below their competitors which attacted a lot of people
-The majority of people still don't own an HDTV, Nintendo figured that as a result, HD graphics would not be necessary to suceed this gen
-The promise of motion control and generally a different approach to gaming attracted a lot of people to the system
-In addition to being b/c with all gc titles, Nintendo has been offering classic titles via the VC to attract old school fans
-Nintendo still has great brand loyalty, their first party titles are basically guaranteed $
-They managed to tap into an extremely large, generally untapped market(the non/casual gamer)
Anyway, just a few reasons imo why the Wii has sold so well thus far.
The only teeth strong enough to eat other teeth.
