Honestly the way the touchbar handles volume is about the only thing I like about it. It's also literally the only thing I use on it besides the software "ESC" button.
I probably use this feature 10-20 times a day, and it would be a noticeable irritation for me if it was key based. I am disappointed they're dropping the touchbar in upcoming M1x/M2 macbooks, I would definitely have preferred a touchbar. Apple, are you seeing this?