I think that, in almost every case, allowing literature to be read by young minds is a good idea. Let kids read bad books. Let them experiment with stupid ideologies. That is where they learn. I read some terrible books. L. Ron Hubbard's "Battlefield Earth" inoculated me to his ideological machine of Scientology. Some fantasy novels which were very engaging for a young mind, approached with the wisdom of age, I no longer consider all that good. R.A. Salvatore inhabited a world with intelligent and human-like "goblins" and other "monsters", wherein the rules of the fantasy permit mass murder of "monsters" to be a good, morally permissible thing. And the first rule of Terry Goodkind's "Sword of Truth" series is that people are stupid and can be easily tricked into believing whatever they want to believe. It's an Objectivist's power fantasy.
Eventually, I think many people have the intellectual hygiene to attempt to sanitize their minds with higher degrees of literature. There is a difference between "Twilight" and "The Symposium". Both discuss love. Why choose the latter when presented both? Just a hypothetical question.
What sorts of literature should be banned? In an ideal world, none. If a book has enough value even to make it to a shelf in a library or book store, then it is probably good enough not to melt your brain. An extreme example of literature that defies any degree of taste is Marquis de Sade's "120 Days of Sodom", the eponymous philosophy of "sadism". But no child is ever going to try to read it, and most adults will give up a few dozen pages in, if that. It does, philosophically speaking, contain some literary merit. It shows how the rich, bored, and powerful take pleasure in causing excruciating physical, emotional, and sexual pain to those they see as less than them.
I'm reminded of this quotation by John Stuart Mill: "If all mankind minus one, were of one opinion, and only one person were of the contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind."
This should be a guiding principle to protect vulnerable pieces of art and literature.
Just as I have read Douglas Adams ("Hitchhiker's Guide to the Galaxy"), Piers Anthony (Xanth novels), Ursula K. Le Guin ("Earthsea" series), J.R.R. Tolkein ("Lord of the Rings"), Noami Novik ("Temeraire"), Robin Hobb ("The Farseer Trilogy"), and Liu Cixin ("Three Body Problem"), so I have also read almost everyone mentioned in The Philosopher's Drinking Song. Aristotle's "Nicomachean Ethics", Nietzsche's "Beyond Good and Evil", John Stuart Mill's "On Liberty", Hegel's "Phenomenology of Spirit". All have shaped me; all are worth reading. It almost goes without saying that the philosophers do not appeal to everyone, but the fiction is meant for a mass audience.
I cannot say that I have ever regretted reading a book. Sometimes I lose interest and drift away for a time, but often I come back later and try to finish. The advantage of a book is that you can stop half-way through and finish it later. Anyway, I try to make a habit of reading for at least half an hour per day, even if it's not consistently on the same piece.
I fully agree with Schopenhauer, who said: "buying books would be a good thing if one could also buy the time to read them; but as a rule the purchase of books is mistaken for the appropriation of their contents."
I have placed a few works on a bucket list. The oeuvre of Nietzsche, which I read in my late teens and early twenties. Hegel's "Phenomenology of Spirit", which I read in my early thirties (although honestly, understood it poorly). And now, as my Mt. Everest, is Marcel Proust's "In Search of Lost Time", which I started reading in fits in my mid twenties, and on my current read-through have only made it four of six volumes in. It clocks in at nearly one and a half million words, close to twice the length of the Bible. I plan to read the complete "Gulag Archipelago" sometime, having narrowly finished volume one (after reading Solzhenitsyn's “One Day in the Life of Ivan Denisovich”) . It provoked intense feelings of depression.
The ”Diary” of Anne Frank, however, lists as the single most heartrendingly depressing work I have read and finished. Reading it as an adult was interesting, because I empathized more with the adults in the story than the young narrator.
Another book I've never quite finished, due to interruptions caused by my excitement of picking up new novels, is "The Tale of Genji" by Murasaki Shikibu, the earliest "novel" in history, written by a lettered noblewoman in ancient Japan. Another early novel that is lying half-complete in my pile is "Don Quixote" by Miguel de Cervantes, a book that helped birth Western literature. Chaucer's "Canterbury Tales", an early contemporary of Shakespeare, similarly, lies half-read beside my bed.
Have I read books that leap onto banned books lists? Indeed. I make a point of it. If something is so disturbing that people in power do not want me reading it, that is all the more reason to read it. "Maus", "A Brave New World", "The Handmaid's Tale". By banning a book, someone is making a statement, and I impulsively disagree with that statement.
However, although no book is written for everyone, the art of reading itself should be. Find what appeals to you. Fiction or non-fiction. Classics or mass-market paperbacks. History or theoretical physics. Poetry or journalism. Self-help or murder mysteries. Feminist philosophy or autobiography. No matter what, you will not regret it.