Nintendo likes to keep it's IP on it's own hardware, but Square Enix (for one) has released several of it's most famous RPGs on Android (most of the Final Fantasies, Chrono Trigger, etc.).

Updates do have to be made to support a touch interface, which is why I think you're request is not a trivial undertaking for most companies. RPGs work, but I can't imagine playing a game like Contra on a touch screen.