Pyramid is a very used symbol since the dawn of time. I actually don't know what it truly mean, in all of its form and all of its use (the sense is different from a tradition to another), but I think that the sense it holds today in the satanists cult is domination.

Now, about the eye, the one used in the very well known symbol from the illuminati, still used in freemasonry is the eye of horus. Its true sense, from my point of view, is the symbol of the antichrist. Because the antichrist, may actually be one-eyed. That's why this symbol represents him so accurately.

Moreover, eyes have actually a psychological impact. I came across a study, that I don't find right now, about this exact impact. I'll try to find it later.

We live in the age of psycholy, and so psychological manipulation.
Moreover, when you dig, you'll find that a lot of artists actually are occultists. Some would even say in plain side that they practiced at some point witchcraft. Since most of people are watching movies, or are simply atheists, they don't care. When you think about a witch, you think about Ermione Ranger, not about a dirty evil thing that needs to be killed. The same goes for vampires, demons (naturo, a shit tone of other mangas etc..).
Thanks Hollywood.