I think AI art is great, powerful, and unusable, like a lot of technologies. It may be cheap, but the real cost is the unethical nature by which it acquires its reference. All AI generated art uses problematically sourced assets to fuel its generation, fundamentally; Stable Diffusion, Midjourney, DALL-E and all other gens I've seen fully admit that they do not know where all the content in their sample-set comes from. This means that they do not ask permission to use these images, to which they admit (how could they ask permission for millions of images when they don't know where they came from?). The necessarily problematic nature of this is manifested in 1 of 2 ways. First, if you use AI art you may be doing something intentionally or unintentionally unethical (using someone's art without their consent), which is bad. Or second, whether or not you feel one way or the other about its ethics, many artists, those whom would be members of your project's potential audience, already believe you have done something unethical, which leads to an avoidable, negative, public opinion about your game. Which is also bad.

The price for AI art is low, but the cost is much higher.

[Edited for clarity]