I mostly agree with you except that the experience of every reader is different. What we find boring because of our over-exposure to similar themes might be exciting for someone who is encountering them for the first time. So if those readers are your targets, then I don't see anything wrong with GPT-3 aiding us.

In any case, do you mind recommending me some novels that you find exciting and do a good job of describing character and other details without being boring or generic?