The knobs have something... visceral... in the way they feel. Few pushbuttons can do that, and touchscreens cannot.
Touchscreens took away the haptic aspect of interaction with electronics. I will grudgingly admit the usefulness and flexibility of this kind of user interface, but an important part of the operator experience is just... gone. Now everything feels the same, like a glass slab.
Design with knobs or even toggle switches is difficult these days. Everything has to be controllable remotely over some sort of data bus (which is good), but then the user interface has to match the inner state of the machine (which is important), and there's just no way (cost effective) to match the knob and switch position to a remotely induced state change. (Built-in servos and solenoids are possible but then we trigger the cost-effective exception.) So in the better case it is buttons and rotary encoders, in the worse case just a glass slab. Oh well, welcome in the future. (And, when we're there, where is my flying car?)