I don't think it's so surprising. It's probably the same effect that keeps giving up Hollywood movies based on popular comic books or TV shows. They need to make money, and the safest way to do that is to go with whatever has gotten good ratings in the past, and there is no denying it - ghost crap gets the ratings.
Add to that the fact that it is by far and away the cheapest TV you can make, and the network execs will need no further convincing.
This is why public television is not just good, but necessary - public television that is not ratings conscious (transmitting bland garbage - catch the reference :) but charged with producing quality programming
There's only one "positive" I can see coming from this disturbing trend, and that is Hollywood finally giving the green light to "Ghostbusters 3!" While my young children are watching "Ghost Whisperer" I make sure that they understand that "Ghosts" are not real and it is only a TV show. At least the "Reality Show" format makes sure that they are not dragging in any specific religion, but rather that there are some "restless spirits" left on this plane of existence and that folks have have been hallucinating- I mean "sighting ghosts" all throughout recorded history.
Granted, I gave the idea of such spirits some thought a while ago, and from a scientific point of view one might argue that the "Law of conservation of matter and energy" might lean towards their actual existence. However, until science can definitively explain exactly what a soul is, measure its presence with instruments, and use such to in turn prove a "ghost" I will remain skeptical. I have an open mind for the truth, but not speculation. I enjoy fiction for entertainment purposes, but I rarely respect anything that pushes a religious agenda...
I'm not sure it was always the case. There was a time when Albert Einstein was a celebrity (if that had been today, you can forget about all those posters, no one would have ever heard of him), a time when romantic leading men like Cary Grant could portray intelligent, accomplished people. H.L. Mencken was one of the most popular journalists of his day and Mark Twain was insanely popular. Even as late as my childhood (80s) the right wing consisted of economical conservatives, elitists, and the left was mostly portrayed as hippie "duh" types in their stereotypes.
I think the anti-intelligence movement has moved forward greatly in the past 10 or 15 years, to the position it currently commands.
Alas, it doesn't so much affect the pseudo-science and woo, that was always around. But the outright anti-science is relatively new