Because Guitar Hero and DDR are highly successfull and now part of the gaming culture. Wiifit before it's release is easy to criticise,since it's coming by a company that the main arguement against it's huge reclamation of #1 in the videomarket is, the destruction of gaming as we know it by catering to the "casual' crowd. Once Wiifit is a hit, critisism against nintendo is going to move to other genres.
"You won't find Adobe here in Nairobi"