If that's your position, I have some sympathy for that but I'd say that the difference is that in a world where AI art can be generated at the push of a button, we end up in a world where it's impossible to determine if a piece has been made by human hands. The cultural equivalent of grey goo.
To me there's a big qualitative difference between some art being bullshit and (effectively) 100% of it being bullshit. Of course that includes narrative art as well, since GPT-N language models are already pretty capable in that department and will only be getting better.