A touch screen is more expensive than an injection molded plastic knob, even if the actual interfacing of the controls is easier.

I take the point that it’s simpler to integrate with how many buttons, dials and controls newer cars have, but I think the proliferation of those bits is part of the same issue. A lot of stuff is being added not because people find use in these things but because companies feel they need to add them to appear like they’re tech forward.