It's all about doing it right. Back in the day when the technology wasn't there, they tried to hide the monster from view because, well, they couldn't make it look very scary. But in doing so, they unwittingly allowed the viewer to create a horror of their own in their head, which is infinitely more scary than some CGI monster you'll see. When film makers embrace this concept, horror can be done right. We saw some of that, I think, in Cloverfield, where despite putting a ton of effort into making a very detailed monster that had a lot of thought put into it's appearance, they mostly hid it from view. You'd get glimpses of the Cloverfield monster from a distance but it wasn't until near the end that you ever get a really good look at the monster. If you want to make a good horror movie, provide the viewer with just enough to allow them to fill in the blanks themselves, because the unknown is so much scarier than the known.