Cultural inertia: until recently, you couldn't just press play and get even a wide selection of music: for most of history, if you wanted music, you had to make it or hire someone to do it for you.

More recently, you had to go to the store and buy it, which meant you didn't have much variety.

Today, learning an instrument is for social status, inheriting the shine of the past, where music was rare and costly. The reason to learn an instrument today is because the former situation was romanticized.

It'll probably take a generation before people ease into guilt-free enjoying infinite, fully generated music.