Artists want to create. They do not want to tweak prompts and click "Generate" repeatedly until the output matches their vision. I would find this maddening.

But this wouldn't make sense anyway. Game companies won't foot the bill for real-time renders of your character, let alone a world of generated NPCs. If/when costs are low enough, and players accept a recurring subscription to play games, then this could happen, sure. No way in hell will artists be available in real-time to keep the generated imagery consistent.