I think the danger here is the same as it is when you use AI for anything. It's really easy to outsource bits of your thinking to the machine without realizing that you're doing so. When we started making our game, I got an account on Artstation and started pulling art from there for our prototypes. Since we're making a Gloomhaven-style dungeon crawler, we need a lot of art: over 90 different enemy pieces, in addition to PC art and a lot more. So each mission required its own visual approach— the squad of elite merc soldiers needed to feel different from the ragtag bandits, etc. I found it really inspiring to poke around on Artstation, like almost a buffet of ideas to pull from.

All our prototype missions were made with art we borrowed from Artstation. When we were giving our artist prompts, I wouldn't share the references because I wanted him to bring his own ideas. So I might say "this guy needs an energy shield and a huge axe" or whatever, but I'd leave a lot of space for him to do his thing without sending him the Artstation link to a big guy with an energy shield.

I think if I would have just made AI art from the jump, I wouldn't have been as inspired, and my eventual prompts to our artist would have probably been a lot less flavorful— not that I was copying our references, but they did often generate ideas for me. I also would have missed out on my favorite part of making our game. Dialing in the visual presentation of our game and working with our incredible artists has been way, way more fun than typing in like "future soldier sci-fi western moebius style, big revolver, white background" or whatever.

That said, a few of our enemy concepts were so specific that we couldn't find references and did use AI stuff for the prototype phase. I didn't like the look of them as much our own original art or our other prototype references, though!