I would expect more data to make ai music generation better
An earnest young lady with a guitar can already sing a light jazz version of 'Highway to Hell' or whatever. Just go to your local cafe to hear it. The objective quality is terrific.
In the past, this wouldn't have been made because the end result is subjectively banal. But now people with no taste can churn it out by the thousands of hours for free.
We aren't really short on music. Diluting the good stuff with 100x more mediocre filler is not a good thing.
If AI generated music ever actually becomes good then that's another story but that is quite a way off.