I too have thought about going the tablet route. One of the main problems I have with that though is hooking up a backup camera. Is there such a tablet with video input? If that is possible, is there some way or some app someone has developed that automatically switches to the backup camera when the car is put into reverse? If there is some solution, show me the way.
As for the resistive touch screen, my line of thinking was that I wanted something stable. When you're in a car, things can get bumpy and if you have something as sensitive as a capacitive touch screen, you are more likely to accidentally open a wrong app or choose a wrong setting. I thought this was the reason why most cars still use resistive over capacitive even if it is "old" technology (unless we are talking about the Model S).