We're not talking about Assassin's Creed or Prince of Persia. And yes, there's a difference. Assassin's Creed and PoP weren't announced for the Wii. Where-as, when Dead Space was announced for the Wii, everyone thought it was going to be just like the others. It could work very easily, just downgrade the graphics a bit, and the controls would be like RE4. Nothing hard about that.
I fail to see how porting a game to a console makes a game a cash cow. And rail-shooters do work well for the Wii. But I didn't see people complaining about RE4's controls on it either.