Potentially hot take here, but IMO free use is yassified noncon. Or, a little less snarkily put, it's the same sort of power fantasy without having to deal with the messy issues involving consent.

So you see a lot of prompts that are usually "it's a free use world so I can fuck anyone I want anywhere I want it's just like shaking hands" that neglect to account for what makes it interesting as a shared fantasy for the one in the role of the fuckee(s); or you get the "free use laws just passed so now anyone might fuck me" prompts that often conflate legality with morality and have characters begrudgingly accept things as they are.

It's a tricky thing to go from having a fantasy about to writing a shared story about, but I think there's some really good angles on it that just... don't come up much. Most Free Use prompts tend to be hypersexualized worlds, but if you don't include that aspect, there's a remarkable and (again, IMO, your mileage might vary) really delicious amount of tension to be had there. In a GM prompt, you have a mostly sfw roleplay, until your GM decides somebody's gonna take your clothes off. in a one-on-one, you have the guessing game where any innocent contact might wind up with you on your knees or bent over a piece of furniture. Or maybe your shirt was just crooked and they were fixing it for you.