Right out of the gate, you know that whatever aliens, mummies, or undead raccoons you see in a horror movie aren't real -- so you can't be legitimately afraid of them. You have to cooperate with the movie for it to work. Of course, when the filmmakers are competent and take their job seriously, they will do their best to help you, using fangs, claws, and blood-curling screeches.
These aren't that. In all these cases, filmmakers either failed to grasp what makes a person feel fear, or just didn't care. Maybe they were mocking the human folly of actively seeking to shrink from imagined threats. Whatever the reason, they delivered these... things. You won't be afraid of them, no matter how much you try. But maybe a couple will cause you to scratch your head in bafflement, and hopefully, that'll be substitute enough.
Source: The Atlantic