I completely agree with this theory. It makes perfect sense to make a universe that is based completely on music.
Music is complex and simple at the same time. Most people would explain it as Sanderson explained it, "The noise comes from the open end" while others would explain it like, "the way the wind goes through the mouthpiece coupled with the position of the valves, allows the vibrations to produce the note that we hear from the bell of the instrument".
With the Cosmere, we are left in the dark about the true nature of music in the universe, but we are shown little pieces on each planet that allude to its greater function in the Cosmere.
Oh and also it's about dang time we finally see you on here Terisen It took you long enough to post something here, among other things that we talk about often, so officially welcome : :