> What's the point if human-made art isn't interesting or artistically worthwhile?

Because it is a human making it, expressing something is always worthwhile to the individual on a personal level. Even if its not "artisticallly worthwhile", the process is rewarding to the participant at the very least. Which is why a lot of people just find enjoyment in creating art even if its not commercially succesful.

But in this case, the criteria changes for the final product (the music being produced). It is not artistically worthwhile to anyone, not even the creator.

So no, a person with no talent (self claim) using an LLM to create art is much less worthwhile than a human being with no/any talent creating art on their own at all times by default.