If I'm having a dry spell I might use AI to give me ideas, but it's usually just the headlines, and it often generates disappointing and boring stuff so I don't think I've ever gone with it. The only thing I've found AI to be any good at is generating names for people and stuff.

How do I feel about players using AI? Bad. I used to ask players to write backstories, I don't anymore. If a player doesn't feel inspired to write a backstory then they shouldn't write one. Instead I'd rather pose some leading queries and get a backstory that way. Simple questions like "where is your character from?", and "why is your character in this quest?", and "from the party, name at least one that your character already knows".
When a player has cool ideas I'll basically always use it, either build something around it or find a way to incorporate it. Some players do this often, some never.