IF it is the case that the appeal of ghost stories, the interest in the macabre and spooky, derives from, reflects, the biological realites that everything interpenetrates and is interpenetrated, that would explain the generalized interest -- the appeal of the appalling.
However, that phenomenon, the appeal of scarry stuff, may also reflect humanity's awareness of a castrated god. Which is to say they have not digested the logical consequences of man's binary constructions and the lingering sense of inadequacy of the modern conception that you can just lop off the transcendent and pretend that solves a problem, makes them uneasy.
Now I cannot think of a third explanation, but it will come to me. Nothing is really explained without three perfectly good sketches. Minimum of three. Sorry Occam.