I mean, even if could produce generic metal would it produce Igorrr? Meshugga? Tim Henson? Baby Metal? All of these are driven by other things then just producing metal. I agree pure AI music would properly rejected unless there was some point to it. I could see it have some part, but then as a weird instrument. Take a model for music, randomly mutate internal weights and then let it produce a drum beat. Keep doing that unless you hit some limit and perhaps that is interesting.