Quick, precise fighters, for one - 2-d action games like megaman, castlevania, etc - many 3-d action games - any kind of game that requires either fast, precise action or is built on abstract concepts that concern themselves only with the standard type of controller will benefit from the ability to use a more standard button array.
Don't tell me you won't even miss holding a controller in your hands. The Revo's new controller concept is fantastic, but hand-motions and gesturing don't lend themselves to EVERY game - a game like Resident Evil 4, Mario 64, Wind Waker, Pikmin, FPS's, Adventure games etc. would be AMAZING on the Revolution's new controller, since the control is meant to be natural, fluid, and accurate but not to a lightning-fast degree - but a game like Soul Calibur or Guilty Gear X/2 or Megaman X, even if they would benefit vastly from the motion sensing, still will also benefit from the trappings of the controllers of yesteryear.