Vampires aren’t as big as they used to be.
For a while werewolves were making a run for the money, but that went to the dogs. Then came zombies, and they are still rambling along. Angels were big for about a moment, but then they flew away. Aliens were tried, but never really landed. Fairies are still trying to take off.
Still vampires creep around in the darkness. They are not favorites of agents and publishers, but they still hold some of the market. And they are very much alive and well in self-publishing.
Readers are still enthralled with paranormal. Readers of romance especially have always been looking for a bit of fantasy mixed with their real-life aspirations, so these larger than life paranormal characters still attract those readers. And, you must remember, romance readers can be voracious.
Some may believe paranormal is trite, but as long as vampires sell I will name them. Send me your blood-drinkers, your demons, and fiends. They are much more exciting to name than every Tom, Dick, or Harry.