It is more profitable to release a game on the pc then the wii, for a huge amount of reasons (correct me if im wrong obviously).
Firstly no royalty fee's
Secondly a far larger casual market (the games that sell to casuals on the pc are even smaller games on average then wii casual games).
Thirdly digital distruibution. Steam has 15 million users. You don't pay physical distribution costs etc and hence its cheaper. Steam is only one of many.
Finally massive indie scene (bigger then all the consoles combined). You don't need to be a huge developer to release something on the pc.







