No, the "teach me about the world and myself" is not a criteria for being a good book, quite the opposite. It is not because a book teaches you something that it is good, it is because it is good that it teaches you something.

But why or how is it good, then? Well, usually because the writer is a good writer (but not always, some books have no writers, or are good despite their bad writers).

And a good writer is just someone who has a very itchy scar somewhere and would die if not using writing as a bloodletting.