I think a lot about this topic. I have a double-life as a classical saxophonist, and something that interests me is the disjuncture between form and function in electronic instruments.
I think my favorite instruments are those with limited function, but with high capacity for interacting with other interfaces (given that many of the people on here make music with modular setups, I suspect this is a common sentiment).
I think that a good way to think about this topic is not looking for interfaces that “get out of the way,” so to speak, but that promote interesting dialogue between musicians, engineers, designers, composers, and the interface itself. In music, this dialogue takes the form of music (and forums like this one).
From a research point of view, this comes from Bakhtin’s “dialogicality.” There’s a good deal of writing on this topic in the fields of UX and design. These are just two examples, let me know if you want some more or some primary resources. I’m interested to hear others’ thoughts on this subject!