Obviously, the main benefit of it as a medium, both for producer and writer, is that it doesn't cost anything to realize grandiose dramatic visions. I've been able to write about shipwrecks, the battle of Thermopylae and the trial of Oscar Wilde, all without having to worry about a budget at all. As to its progeny, the only audio I have done is an abridged recording by Richard E. Grant of The Vampyre in the States, published by Pocket Audio under its US title Lord of the Dead . Similarly, your writing seems to show a balance of these two elements. However, in the 20th century, horror literature has shifted from the purely atmospheric British horror writers like Algernon Blackwood or M.R. James to the largely event-based horror of Richard Matheson through Stephen King.
Horror works best when it is an interplay between writer and reader.
Both Vakhel Pasha's castle and Lilah's opium den drew heavily on imagery taken from de Quincey. But I always try to cast them as the expression of spiritual or psychological horrors. It's not a particularly original point, but the truest nightmares are bred by the brain. Early fictional vampires tended to be depicted as totally evil, amoral supernatural beings, whereas nowadays they have been largely humanized into cultured, hedonistic and though often largely moral, potentially dangerous uebermensch . I'm not sure I quite agree with your description of the evolution of the vampire.