Unfortunately the Wii seems to be in a vicious circle at the moment.
Developers don't devote too much time an money to develop for it which means that low quality games and ports are produced, which means that Wii owners don't buy many non nintendo games and as a result 3rd party games don't sell as much which makes them reluctant to produce any big budget titels to begin with....
PSN ID: T_Gears
End of 2009 ltd sales:
Wii = 67-68m
X360 = 38-39m
PS3 = 34-35m
Prediction: The PS3 will surpass the 360 on weekly sales after it drops to $299 on all regular weeks (no big releases).