Let's say we have a painting of of girl daydreaming in castle. Which of the two backstories sounds more intriguing?
1) It was generated by an AI program in 30.67 seconds
2) It was painted by a 90-year-old blind man in Syria who could only afford one brush
Hands down, option 2 is the most intriguing. AI may be able to generate some very cool things, but humans are often not just interested in the thing itself, but the backstory behind that thing. AI will never have that advantage. For a video game analogy just think about the story behind the creation of Stardew Valley.
And let's not forget, a lot of these AI programs get their content to begin with by scraping samples from human-made art. If humans completely stopped making art, then the AI generators would only be able to sample their own creations which would ultimately result in some very predictable and boring results.