My local library has a section for science fiction books but no section for horror titles. If you want horror masters like Stephen King or Richard Matheson, you have to look through the normal "fiction" section. This could mean one of two things. The first is that horror is now good enough to warrant inclusion with the regular section. But the second, and most likely, is that horror is not good enough for its own section. It occurred to me that maybe this thinking applied to movies as well.
Back in the 1950s, sci-fi and horror were pretty much mentioned hand-in-hand, as if they were both part of the same depraved, bottom-feeding segment of popular entertainment. They were often uttered in the same breath, and often as something childish, or as a corrupting force of children. The best and most popular examples from the 1950s were all sci-fi horror hybrids: The Thing from Another World, The War of the Worlds, Invaders from Mars, Godzilla, Creature from the Black Lagoon, Them!, Invasion of the Body Snatchers, The Blob and The Fly. These were, more or less, movies about things that had gone wrong with science (or nature, or both) and began to run rampant.