AI is incredibly overhyped right now, and all the fanboys gushing over it are fucking retarded, hucksters, or both, and companies using it to replace humans are jumping on the bandwagon far, far too early.
Right now, LLMs can't do things like answer "is n a prime" correctly, even for the kind of small values of n that you can look up in a table. If you want to write something bland or average, then go ahead (maybe it'll put Obsidian out of business lol), or use an older model where things only make sense locally and make a watered-down Xavier Renegade Angel RPG.
Current generated art is also either the nicest-but-blandest-looking thing in existence, or some hideous monstrosity. Watch out if you get too specific, though, because some models have a limited training set for certain things, and you'll be at risk of replicating/plagiarising existing art from the training set (which has happened with Midjourney with the famous green-eyed Afghan girl photograph) and good luck not getting sued over that if you decide to share the game, or even screenshots of it.
Code-wise, it can be good for simple functions (i.e. things most devs would copy-paste already), but isn't trustworthy for anything that can be as complicated as a game, particularly stuff like RPGs. Will a non-coder know that some failing bit of code is almost correct and only needs a small change to work perfectly, or will they go "ugh, this sucks" and generate something else?
Will they be happy that it seems to do what they want, only to be surprised a hidden side-effect has been overwriting or corrupting their other files? A lot of code these models have been trained on will not have good documentation, unit tests, or a whole bunch of stuff that coders should be doing to make their code understandable and robust, so the generated code might not have this either. There's enough absolutely awful human-written code out there to be worried about anything that uses it to "learn" how to code.
So yeah, you'll be able to make your own games using AI soon, but they're going to be as boring as the current middle-of-the-road game.