Because some times you might need a (possibly) crappy other controller to beat people better than you, but this one seems to have more on its mind than just being another clone.
Full gallery hereNyko has what it plans to be the world's first Wiimote replacement with the Motion Plus add-on built-in. Dubbed the Wand+, the controller will retail for $39.99 and should be on shelves by March. In addition to those fancy gryoscopes, the Wand+ has a matte rubberized back and rubberized buttons that are pretty comfortable to the touch, there's a built-in camera for acting as a "regular" Bluetooth mouse, and the whole assembly is much lighter than a Wiimote / Motion Plus combo.
Expect me to find and post a review of it when it comes out