So many people have tried that I feel compelled to say, "prove it." SMB1, SMB3, SMW, and even Mario 64 all require remarkably precise controls for movement--and I tend to think that moving away from that sort of precision of play moves away from something intrinsic to Super Mario games.

Maybe we need to look towards the DS for inspiration. At the beginning, the touch aspect was heavily promoted and a lot of games came out with only touch controls, that worked mostly well. On the other hand, the DS has one very important feature - a stylus with a sharp point. Even if you do get a stylus for your phone, most have very wide ends, nothing like the precise pen that came with the DS. I sometimes wonder whether if mobile phones had all come with styluses, we'd have better games.