So what you're saying is that the GamePad is like those weighted shirts and wristbands everyone used to wear on Dragonball Z, and a developer who removes the GamePad from the equation has access to more power?
Wii U secret sauce confirmed.
This might be why a game like Bayonetta 2 (which you mention is simply displaying the main action on the GamePad) is able to push the system a bit further than others. And I would mention that so far, Mario Kart 8 seems to be running at 60fps, and will most likely be able to display different action on both screens (for multiplayer).