Earlier quoted context omitted.
You mention the example of romance novels above. There's a schlocky Victorian pulp novel that's of no use to anyone - except that it happens to contain a fantastically detailed description of an abandoned saltings in my hometown that nobody ever thought to record in any way. For me, those two paragraphs are gold. If the novel hadn't been digitised as part of Google's Books Archive Project, I wouldn't have been able t…
Well I guess your one valuable paragraph that matters only to you justifies backing up millions (billions?) of human and soon to be AI generated books, because someone, somewhere, at some time will find a line or two valuable. Maybe. I retract my position, let's back up everything!
What seems banal and useless to you, might be extremely important for future historians, and to be honest, books are pretty compressible and storage is cheap.