>I'm not sorry that we no longer have a monoculture with a generally agreed upon definition of what a "serious book" is

I am. Instead of having something for people reading to aspire to and get to something better, and people serious about books and literature, we just have each person's arbitrary "taste".

Plus leisure reading being at an all time low.

Personal taste is not a bad thing. But it's something people develop, among other things by having guidance and a compass.

Instead, today we build a god of our whims and facile enjoyment, and declare our personal uniformed and under-developed taste the ultimate arbiter.

That's basically arrested literary development.