So, what's the deal with this trope? Well, the page says "classic creepout device". Yeah, I'd say that the idea of having your still-beating heart ripped from your chest is indeed quite creepy. I mean, the heart is pretty important, so it stands to reason that having it removed from your body would be traumatic, even if by some miracle of science or magic or whatever you manage to survive the removal of a vital organ.
But lets face it, the creepout factor from this comes from the whole "still beating" thing. I mean, seeing a heart pulled out without the "still beating" factor is more realistic. Okay, maybe not realistic, but realistic within the sphere of fiction. I mean, it's pretty standard Schwarzenegger or Rambo material.
But the fact that the heart is still beating just ups the creepiness to a whole other level*. I mean, it adds a supernatural element to what was just gratuitous violence. I mean, at first it was relatively normal, but now you're dealing with some serious voodoo crap or something. Before, there's still a chance that you could take out whoever the heart-rip-out-er is, maybe shoot him with a bazooka or something. Now, killing the guy might just turn him into a zombie or something.
And that's without bringing up the metaphysical implications. I mean, ever since ancient times the heart has been considered the seat of human emotion and/or consciousness. I mean, now we know that its main job is to pump blood, but we still use it symbolically. I mean, Wikipedia has a page on it and everything. You know that it's important when Wikipedia has a page on it.
In short, hundreds of years of symbolic use mean that we (subconsciously at least) equate the heart with the soul. So not only is that guy getting gruesomely killed, he's pretty much having his soul ripped out.
But yeah, the whole heart ripping this is, in fact, pretty creepy. But then, we should expect this. I mean, with all of the symbolic significance (and medical significance), it makes sense that this sort of thing would happen.
And you don't really even need the "ripped out" component for it to be freaky. A guy named Edgar Allan Poe wrote a little story called "The Tell-Tale Heart". And yeah, it's pretty creepy. Even though the heart isn't actually beating. Actually, that might make it worse.
So in short: Heart = inherent creepiness, especially when it's not where it's supposed to be.
Heart = Useless power.
Heart = Useless power.
Unless it's in the right hands, at least.
*I'm aware that cardiac tissue can, in fact, keep beating on its own. But it doesn't keep doing that indefinitely.