Take your eyes off the road, find the button/knob, do the adjustment while watching, then eyes back on the road, versus look at a screen, do the adjustment while watching and eyes back on the road. There's no real world difference.
Some people say they can adjust with knobs/buttons without taking their eyes off the road, but the reality is the vast majority don't. They want to see feedback either from an indicator on the knob, or a pilot light or a number readout. Radio volume is about the only adjustment where visual feedback isn't required, and pretty much everyone has redundant volume controls on the steering wheel now.