I believe the keyboard is only meant for typing. Having an offscreen textfield for when the keyboard shows up would be really weird.
Also, it'd be weird having one hand on the keyboard and one hand touching the screen at the same time.
The purpose of a non-physical keyboard and multi-touch is for developers to rethink ways of implementing games. From on screen controls to just general tapping.
The iPad isn't a console device nor was it meant as a gaming device either. I think it was meant for books/magazines/newspapers and internet.