Here's my rule: Anything in my Chevy S10 that you control by turning a knob, moving a lever, or momentarily push a button? That needs to be a physical control in a car. Anything where you push and hold a button, or mash a button multiple times (like setting the clock or turning off the DRLs respectively) can be moved to a settings menu in a touch screen. These things shouldn't be done while moving.

And no, touch sensitive single-function panels like the climate controls in my father's Avalon are not good enough, it needs to be a mechanical control that you can feel for without activating.