If you don't like it that's fine. While you may find them dumb, cardio exercises, strength training, and yoga go a long way towards keeping people in shape.
Sure, using the Wii Fit may not get you results as fast as hitting the gym on a regular basis but it's can be pretty good exercise and many people find it entertaining.
The board can be used in other games as well. I have both the Xbox 360 and Wii versions of Shaun White snowboarding and the Wii version on the balance board is a heck of a lot more fun than using the 360 controller and I work up a pretty good sweat. I'm looking forward to trying Skate It now.
Not really sure why you're so down on the thing.