With a knob, you always could stop what you are doing and look back at the road and then continue. With a touch screen, you need to find a button and touch it without looking at the road, or you need to do it from the start again.
replyI have this knob and I don't understand your point. With the knob or the touch screen, you need to look at the screen to see what you're doing. The knob merely controls a cursor.
replyI find the knob considerably more distracting. First you have translate the motion of the knob to the cursor moving on the screen. Secondly, you have to cycle through all the options so you have to spend even more time looking at the screen. It's significantly faster and less distracting to just reach out and tap the button you want.
Other physical buttons are great but the knob is a terrible UI.