One issue is the legality is much more risky than with visual art. While there's been talk of artists suing AI-art companies for using their art in training sets, and generating images "in their style", it isn't clear if there is a real legal case to be made. In music, artists have been suing each other for years over songs that sound superficially like each other even if the artist being sued didn't really intend to copy. I'd imagine AI music would run into similar problems.