I agree, there is certainly potential there. However, much in the same way playing street fighter is crap on a keyboard compared to a joystick/pad and any FPS is crap on a controller compared to a mouse + keyboard, a huge portion of game types just aren't suited to the 'slate of immovable glass' form factor.
Imo, mobile gaming is good at:
- The tiny subset of games where the controls are naturally dragging your finger over glass (Fruit Ninja, those airplane landing games, not much else)
- Turn-based games where the primary form of interaction is suited to a one-click mouse / finger. Turn-based because there is not enough feedback for accuracy in real-time games, and because it means you pick them up and put them down really easily (as long as state is remembered) which suits on the go play.
So stuff like Civilisation, turn-based 4x games, final fantasy style RPGs and XCOM style games are all good deep game genres that will hopefully make a competent jump to mobile.
I see that Frozen Synapse (XCOM style-ish) is coming to iOS, which is particularly awesome (more awesome if it was on tablet android, but that's just my selfishness talking)