The difference is that code is functional, and the product is the output of the code, not the code itself, whereas music is the thing in itself. I'm not inherently anti ai-creations, but the bar is higher for style in aesthetic domains than functional ones, so AI art/writing/music/etc needs to be heavily filtered/massaged/etc. Plenty of writers/artists/musicians are using AI like an idea generator/scaffold then recreating/enhancing the outputs and going under the radar, it's just the low effort people that everyone sees.