I think that discussing this subject in the abstract, with some ideal notion of a tool that generates perpetually enjoyable stories misses the thrust of the general objection, which is actually mechanistic, and not social. LLMs are not this tool, for many (I would say most, but...). LLMs recycle the same ideas over and over and over with trite stylistic variation. Once you have read enough LLM generated/adapted works they're all the same and they lose all value as entertainment.
There is a moment I come to over and again when reading any longer form work informed by AI. At first, I don't notice (if the author used it 'well'). But once far enough in, there is a moment where everything aligns and I see the structure of it and it is something I have seen a thousand times before. I have seen it in emails and stories and blog posts and articles and comments and SEO spam and novels passed off as human work. In that moment, I stop caring. In that moment, my brain goes, "Ah, I know this." And I feel as if I have already finished reading its entirety.
There is some amount of detail I obviously do not 'recall in advance of reading it'. The sum total of this is that which the author supplied. The rest is noise. There is no structure beyond that ever present skein patterned out by every single LLM in the same forms, and that skein I am bored of. It's always the same. I am tired of reading it again and again. I am tired of knowing exactly how what is coming up will come, if not the precise details of it, and the way every reaction will occur, and how every pattern of interaction will develop. I am tired of how LLMs tessellate the same shapes onto every conceptual seam.
I return now to my objection to your dismissal of the value of insight into the author's mind. The chief value, as I see it, is merely that it is always different. Every person has their own experiences and that means when I read them I will never have a moment where I know them (and consequently, the work) in advance, as I do the ghost-writing LLMs, which all share a corpus of experience.
Further, I would argue that the more apt notion of insight into the work is the sole value of said work (for entertainment), and that insight is one time use (or strongly frequency dependent, for entertainment value). Humans actively generate 'things to be insightful of' through lived experience, which enriches their outputs, while LLMs have an approximately finite quantity of such due to their nature as frozen checkpoints, which leads you to "oh, I have already consumed this insight; I have known this" situations.
If you have a magic tool that always produces a magically enjoyable work, by all means, enjoy. If you do not, which I suspect, farming insight from a constantly varying set of complex beings living rich real life experiences is the mechanical process through which a steady supply of enjoyable, fresh, and interesting works can be acquired.
Being unaware of this process does not negate its efficacy.
TLDR; from the perspective of consumption, generated works are predominantly toothless as reading any AI work depletes from a finite, shared pool of entertaining-insight that runs dry too quickly