The eye coming out of Ash's shoulder scared me far more than, say, the chick in Jason X getting sucked through the small-squared grate into outerspace, or the guy getting torn in half in Jaws.
There are different grades of horror movie. Some people want the sophisticated horror like in Shining. Others want to sit back and watch heads explode like in Dawn of the Dead. My favorite horror movie genre is beasts (mythical or not) attacking people. Monster flicks. It comes off campy but I like the idea of it.
The real point of over-the-top gore is to gross people out. If played right, it can be absolutely terrifying. Most of the time, sadly, it is not.
So what I'm really trying to say is that it's good to have multiple genres of horror at hand in case you have a moment where you don't want to sit back and think about it. Or maybe you do. Or maybe it's cooler to watch a lion rearrange someone's intestine.
To me, most gore in horror films does not effect me like real life gore will. And if I see gore in real life, my first reaction is to assist in any way possible. Stop the bleeding, put the body in a better position, assess the wounds and tell the emergency people over the phone what is wrong before they get there (which helps). Only after the fact am I allowed to be traumatized and cry, or go into shock. One of the two. Time and a place for everything.