If it's something you're reasonably expected to do while driving (so with the car in motion) then you should be able to do it without ever having to take your eyes off the road. Physical buttons let you do that. Between the ones on the steering wheel to control 99% of multimedia, the ones behind the wheel for lights&stuff, and the ones on the center console to control car functions like A/C and whatnot, you mostly hit that target.
Touchscreens force you to take your eyes off the road. You can't fumble around and guess if you pressed the right thing or some random function. This means they are only appropriate for things that would normally be done while the car is not moving. Before someone mentions "but GPS", you should NOT be typing in GPS addresses while driving unless you're using voice. Touchscreen or not you still have to look at that screen for a pretty long time.
And I will also mention the obvious: with everything bundled on the touchscreen God forbid that one single part breaks (due to design choice [0] or simple accident). It renders a good part of the car unusable.
So yeah, I'm good with having a big cool touchscreen but this doesn't mean the basic functions have to be moved there.
[0] https://www.thedrive.com/tech/27989/teslas-screen-saga-shows...