This is just being obtuse and a bit of a cunt.

No, I'm seriously asking. You said that there has to be a price to pay, but I really don't see why. Why can't people be free to do these things? It doesn't harm anyone else.

It's reasonable to create laws to restrict behaviour that harms other people, but that requires the person proposing those laws to show that this is actually the case. And that the restrictions placed by those laws are reasonable and proportionate, not causing more harm than they prevent.

Individual free use is fine, why would anyone want to stop you, individually or even with your friends, being creative? The problems comes when companies with huge resources, influence, and nefarious motives decide to use it.

There is no sharp dividing line between these things. What if one of the adventures I create turns out so good that I decide to publish it? What if it becomes the basis for a roleplaying system that becomes popular enough that I start a publishing company for it?

The problems comes when companies with huge resources, influence, and nefarious motives decide to use it.

How about if one of those huge companies just wants to produce some entertainment that will sell really well and that I would enjoy?

You're not really making an argument for banning AI, here. You're making an argument for banning nefariousness. That's fine, but that's kind of a bigger separate issue.