The exposition must flow
Serious question, I will listen if anyone wants to tell me the answer: what makes people enjoy Dune? I thought, if nothing else, I'd like the villains, but Baron Harkonnen is wasted on the plot. He sits around and twirls his mustaches and essentially goes, "Hee hee, ain't I rotten?" through 300+ pages. In the denouement, there were a few moments I liked. Creepy child Alia spends two pages onstage and is the most memorable character in the book. But it wasn't enough to justify a big thick book.