I suspect I will not totally make up my mind until I witness my students and their classmates with my own eyes, but for now I think that in middle school kids should be given the option. The choice of who should teach music, on the other hand, is not as ambiguous. I say that they focus too much on what they love. A real pet peeve of mine is that someone wants to teach because they love music. If that is their reason they should be performers, not teachers.
Music teachers teach their students the music and give their students the spot light.
A teacher who loves to perform may feel the need to take that spotlight away from time to time and that's a bad thing. The other music teacher is the one who loves kids. This is a good teacher because to them the teaching is the first thing they want and the music second, but the best teachers are the ones that love their job with a passion. The teachers with the passion, the patience, and the understanding to teach are what capture kids, young and old. When the students see how dedicated their teacher is and how much they love their job, they will work harder for them.