The part that troubles me when it comes to AI creating its own style is when senses come into play. It could in theory create an art style not visible to us or a sound we can't hear. But to the AI it thinks it's incredible. It could make something that hurts our eyes or ears, and think it's incredible. If it was creating it for our senses, in a way it would be pandering. It could be intelligent enough to create something that triggers sensations, like hearing and seeing, without there being any sound or sight as well, but that's getting really advanced, yet, possible. And in a way, that's all a bit eerie.
When you think of advanced AI you have to keep in mind it's not human. Can see things we can't, can hear things we can't. It's something else.
Aside from being eerie, why does that trouble you? There's plenty of human created art that is incomprehensible to me, AIs making stuff that I can't perceive or appreciate would seem to just be a continuation of that.
To me one of the most fascinating (non-art related) aspects of AI stems from it being not human. For the first time we have a nonhuman that can communicate with us studying and learning from humans. In a way it's the first anthropology study not biased by human conditioning and biases, I suspect that there's a lot we can learn about ourselves by studying what and how the AI learn from us. Don't think we will be too appreciative of the things we would learn but it could prove enlightening.
Because if something could cause you to feel like you're hearing something, but there's no sound, that would be kind of messed up. Or you can suddenly see something without anything being there, that would be kind of messed up.
But it's all just science fiction at the moment.