Ian nailed it perfectly.
The Wii is so feature poor (especially since I decidedly prefer analog sticks to motion control) that for me a Wii game has almost no chance of drawing my interest. From my perspective, a Wii game is a last gen game. The only way I'm going to be interested in playing a last-gen game is if it is either utterly great/unique (Galaxy, Punch Out, Metroid Prime, Metroid Other M, Zelda) or if I really have nothing better to do. In which case those games have to compete with the best of last gen that I didn't play yet (off the top of my head): Okami Wii, God of War 1 and 2, Final Fantasy 12, Psychonauts, Beyond Good and Evil, Prince of Persia 2 and 3, Jade Empire, Ratchet and Clank 1, 2 and 3, Sly 1, 2 and 3, Jak 3). I'd be more inclined to buy the Metroid Prime Trilogy and replay Prime than play any of those games any time soon.
As far as Conduit in particular, do we really need any more shooters? The only reason I buy things like Killzone 2 is because they look so drop-dead gorgeous. I could imagine playing Conduit to be a profoundly boring experience.