The main problem that I see with Stephen King in particular and modern horror in general is an inability to write a Good that deserves to conquer Evil.
The modern horror protagonist is, at best, less bad than the monsters. In the more splatterpunk side of the genre, the protagonist is not even that–he’s just the one who ends up with the bigger gun at the end of the day.
This is not to say that a horror hero must be a saint, but simply that the things for which the hero is fighting–the security of his home and family, the safety of the population in general, or even just his own life–should be acknowledged to be not just his own preferences, but objectively worthwhile.
Moral relativism nerfs horror. If Joe is trying to stay alive and Blargdor is trying to kill him, the author should take a stand and say, “Joe is right to want to live and Blardor is wrong to want to kill him.”
Instead, modern horror writers rely on increasingly gruesome depictions of violence and cruelty to try to awaken the reader’s sense of moral outrage.
It is from that sense of moral outrage that the horror genre gets its power. A hurricane can kill people and destroy property on a great scale, but a hurricane is not a monster. (Granted, you can write a ripping yarn about people trapped in the path of a hurricane and struggling to survive, but it’s not horror.)
To be monstrous, the antagonist must be not merely hazardous, but also wrong. Wrong in an objective sense–Something That Should Not Be.
It is in the deliberate fostering of a sense of injustice that a writer invokes true horror.
Killing a monster has to more than personal survival, it must be in itself a morally positive act.
Injustice, however, requires an objective standard of justice to be measured against, and that is something that few modern horror writers are willing to portray.