Buying a system just for one game isn't odd, unless you paid an exorbiant price for it or something. I've never quite gotten the logic of people who buy a system just for one game (even if they barely pay anything), because just about every system in existence has at least 2 or 3 games worth checking out, including the Cube. But hey, whatever floats your boat.

I've never bought a system just for one game, I always wait for at least 2 worthwhile titles before I buy something.

If Twilight Princess came out sooner, would it have bolstered the sales for the Cube? Maybe. But then again, if you're going to buy a system just for one game, you're going to be much more likely to do so when you can get the system for a friendly price.