There are some important things worth clarifying here.
First of all, it is my opinion that the main game of Brawl will be playable only with either the Classic Controller or a GC controller. Personally, I think the GC controller will be best, for a variety of reasons. Familiarity, one. The fact that the analog stick is central, two (imagine playing Melee on a PS2 controller). I absolutely love the feel of the classic controller... it is amazing in your hands, and perfect for games with SNES-like control (say, an RPG). But Brawl is not such a game.
Secondly, the Wiimote has 4 buttons, yes, but they're not independent buttons. You can't press up and down together, for instance. If you mapped the buttons to A, B, X, and Y, you will have conflicts. People who jump with Y (me, for instance), wouldn't be able to press jump and A at the same time. It wouldn't work.
Also, a fairly moot point, but you don't have to point the remote at the screen for the buttons to work. The bluetooth receiver in the Wii console handles that. You only need to point it at the screen if you're using the IR pointer.