> If it’s truly better, the market for manmade music will still exist.

That is definitely not true. There are other things that determine what is sold besides quality: ability to mass produce, economies of scale, bullying tactics, etc.

> Not sure how this works, or why it’s so bad.

Because thinking like machines means that we are locked into the cycle of optimizing resource usage to expand and grow forever and not be stewards of the environment. Thinking like a machine means being a human cog in the consumerist machine of selfishness. Thinking like a machine means facilitating the endless growth of technology that furthers us from connecting genuinely with other people in a small community.

Eh, I don't think anyone owes musicians a job, but I also don't think that jobs going anywhere. The painter is still an artist if they use the factory-produced canvas. The musician is still an artist if they use the mass-produced Fender. Or a mass-produced sample library.

> If bland/poor quality art is no longer produced by humans, what’s the loss?

Because even artists often produce bland/poor stuff, sometimes even some that sells well? (or that is recognised several decades/centuries, to be actually great work)