I've seen alot of people complain about how horror movies are not the same as they used to be and okay yeah they aren't the same as they were in the 70's or 80's and of course most of the classics are from those era's but we aren't living in those times anymore.
I think the worst change in my opinion is the vampire genre, there are hardly any vampire movies that are gory or bloody or scary anymore and that i think comes down the terrible franchise of Twilight that made young little girls swoon over a shiny vegetarian non-human killing thing, they see vampires as nice dead people who you can marry and have a child with when actually they aren't like that and cause of those films (i'm sure there are other films that make vampires out to be nice creatures but twilight made it popular) every film we have now about a vampire they aren't the bad guys they are the heroes of the film. What?
We are in an age where most directors want to try and make a new horror film that isnt going to be like previous films but sadly most of the time you can think of a film with similar story lines and plots and that film be 10 times better. We aren't going to go back to the time where slasher films were amazing or exorcism/possession fillms are like The Exorcist (exorcism of emily rose is a very close second) or where vampire movies are like The Lost Boys or Dracula.
So what i'm trying to say is you can't expect films to be like how they were 30 years ago, films change over time its what happens you cant do anything about it.