Horror movies are a dime a dozen now, and most really aren't worth the dime. Horror has become a genre full of CGI gore-fests with little plot, and not much to the acting. Now we're being plagued with a whole slew of horror remakes, none of which are nearly as good as the original. Some of these remakes, such as "House of Wax" don't even deserve to be using the name of the original.
So what caused the decline in horror movie quality?
A misunderstanding of the word "terrified." Think of classics like Psycho, Rope, House on Haunted Hill, The Haunting, House of Wax, and Last Man on Earth. Each of these movies has something in common with the rest. They all terrified people with mystery. In Psycho, we don't see every gory detail of the murders, we see enough to let us know what's going on. In Rope, Hitchcock places the viewer in one room for the duration of the film, knowing what they murderers know. There is a body in the chest in that living room, where the party is happening. We wait in suspense either for someone to find it, or hoping they don't out of nervousness. Hitchcock actually made us care about the fates of the villains. In House on Haunted Hill we are introduced to a group of diverse and peculiar characters who all rub us the wrong way. We hear screams down the hall and run with the others to discover bodies, and terrors. We don't see the murders because our minds, left to their own devices can scare us much more than anything on a TV screen. All of these movies have one other major thing in common: suspense. Suspense being built up continuously throughout the film keeps you shaking and on the edge of your seat the entire time. The reason Rope is so scary is that from the first second to the last there is non-stop suspense. You don't know what to expect at any given second, and so your mind gives you creepy ideas of what it could be.
Now think of some modern horror movies like Nightmare on Elm Street, Friday the Thirteenth, Piranha, Halloween, Insidious, and The Conjuring. They all follow the same pattern: blood, guts, sex, jump scenes, two dimensional characters. When you sit down to watch a new horror movie you know exactly what to expect: the hot girl will get topless(or if it's PG-13 will get into her bra and underwear), the black guy will die first, the bad guy will jump out at you, if there's tense music the bad guy isn't actually coming, lots of gross out killings shown in cheesy detail. That's the problem, we now know exactly what to expect, exactly what's coming. There is no suspense.
There are, of course, exceptions to this rule. Disturbia is an exception, however it is technically a remake of Hitchcock's Rear Window. David Fincher's Seven is an excellent exception as well. They are more exceptions, but in general most new horror movie really aren't scary anymore because they've forgotten that our minds terrify us the most.