You are being very dogmatic with your definition of literature. Literature, as practiced today, is written art. Most of it (and even the best part of it) is just tales created for the simple pleasure to tell a story, that's it. Yes, Dostoevski, Kafka, Tolstoy, et al had this supreme talent to express "truths" about the human condition, truths which perhaps belong to the fabled-Jungian "collective unconscious", but those guys are a minority. Even most of their works can be read and appreciated just as marvelous tales.
Literature, like any form of art, should be rated using the best works, not the worst ones, or the most common ones, or the most recent ones. Who cares if there are a million bad books. That's not the point at all.
