I also worry about the potential to further stifle human creativity, e.g. why paint that oil painting of a panda riding a bicycle when I could generate one in seconds?
Our imaginations are gigantic. We'll find something else impressive and engaging to do. Or not care. I'm not worried. Watch children: they find a way to play even when there is nothing.
The painting technique isn't all that great yet for any of these artbots working in a physical medium, but that's largely a general lack of dexterity in manual tool use rather than an art specific challenge. I suspect that RL environments that physically model the application of paint with a brush would help advance the SOTA. It might be cheaper to model other mediums like pencil, charcoal, or even airbrushing first, before tackling more complex and dimensional mediums like oil paint or watercolor.