Looks like the Zoom G11
might also use them....not sure....
If there's a reason why rotaries with LEDs aren't more commonly used, maybe touch-sensitive knobs would be a good compromise? I.e., touch the knob, the display updates to the current value. Would probably become second nature very quickly. I'm not a hardware engineer, so I don't know if there are cost or reliability issues with capacitive tech or whatever it's called...but it seems like the UX could be simple and easy-to-use...
According to the ME-90 manual, you can see the current value of any knob by holding down the edit button and turning the knob until it corresponds to the value. That's klunky -- I like my design a lot better.