> it's funny to me that the same ideas are masked behind hoighty-toighty music theory terminology that is used almost exclusively in reference to...music that was composed hundreds of years ago.

I'm just coming up to speed on music theory, but my impression so far is that it's reactive, not proactive. We already have music that we like; music theory is about trying to tear it down, identify why we like it, establish base principles that can be used to guide composition, and then use those to create something new. Fairly recently, this had led to "generative music".

I'm finding music theory to be useful to build a more accurate mental model of the instruments I'm playing, which I believe will eventually improve my ability to improvise and play by ear. I think that people who are musical prodigies have an intuitive understanding of those things, but I'm having to build my own understanding explicitly.