It recently struck me how most of the films that, IMHO, were truly scary were the ones that had little or no digital special effects. The reason is simple: what makes something scary is mostly what you don’t see rather than what you do see.
Compare, for example, Alien (1979) with it’s putative prequel, Prometheus (2012). While Alien won an Oscar for special effects, by today’s standards the SFX technology is relatively crude, not all that different from the rubber suits in The Creature from the Black Lagoon (1954).
Prometheus had lavish digital special effects, but Alien is a much scarier film partly because the eponymous creature is only on the screen for a few minutes. The horror comes not from watching what the alien actually does but in the anticipation of what it might do next.
Here’s another example. The Swedish film Let the Right One In and the American remake Let Me In were both good films, and share almost identical scenes and even camera shots. The acting is comparable (the parts are fairly one-note) but the remake suffers from several scenes show the vampire as what appears to be some kind of bargain basement Gollum.
Other examples come to mind. The Haunting (1963) is a truly frightening film even though its only special effect is a bulging door. The 1999 remake, though chockablock with special effects, is utterly forgettable, in part, I think, because it attempted to show what was hidden in the original film.
On a personal note, I once had a long conversation at a Hollywood party with Russ Tablyn, who played the “brash young man” in The Haunting. I recall that he explained how he did all of his own stunts, which was unusual in those days.
As far as I can recall, the only horror film remake that stands up next to the original is the 1979 Nosferatu, based on the groundbreaking 1922 silent film. In this case, the remake works because the director Werner Herzog didn’t muck around much with special effects, but instead consciously imitated the “look and feel” of the original film.
I think part of the problem is that special effects were originally both expensive and difficult to do well, which forced filmmakers to use them sparingly and concentrate more on plot and character development.
Too much dependence on special effects is particularly fatal to horror films, though, and I’ve come to the conclusion that filmmakers who overuse them are trying to paper over a basic lack of talent. It’s difficult to construct empty spaces of dread but easy to be grotesque with gore.
If I might draw a parallel, it’s more fun to be seduced than to get laid. And that’s what really good horror films do — they seduce you into feeling the apprehension of the characters rather than shoving your face into a faked-up reality.