He wanted the cool James Earl Jones voice. He hated being called "Ani" (wouldn't you?). The big black mask is surprisingly relaxing. He heard that the Dark Side throws better parties. K-mart was having a sale on Dark Jedi evil black costumes (from the Martha Stewart line of apparel, of course). Anakin became a contestant on the hit game show, "Who Wants to be a Dark Jedi?" It's not because the Dark Side is stronger; it's because it has a better pension plan. The Emperor triple-dog dared him to do it. He wanted the really cool "Imperial March" music to play whenever he walks into a room. He discovered that Padme is really his sister.