While I can easily see particular situations where touchscreens would be useful, I feel it would be extremely annoying to lose the sense of position afforded by physical buttons.
1. I'm a guitarist.
It's super annoying when a string breaks, even if I'm not using it. My fingers can feel even the adjacency of the string (vibrations, I'm guessing), and I lose all sense of orientation on the freatboard if one of the strings is gone, even if I'm not touching that string.
2. While I'm not a pilot, I spent years testing avionics.
Years later, I can still blindly, through muscle memory, replay sequences of commands in my mind, as actuated by mechanical buttons (LSKs) on either side of the display, and rotary encoders to "dial in" new values (e.g. frequencies).
I would usually run through the settings just with my hands, barely looking, and only double-check the settings as the last step, before actually committing to whatever action I was preparing.
I can't imagine doing something similar on a touchscreen without constantly havng to look.