8 years ago
While it would be less scary to see on a screen in real life it would be just as terrifying if not more terrifying because big things are scary in person. The largest Xenomorph in the canon is a Queen, which doesn't need to be 80 meters tall. In fact, an 80 meter tall Xenomorph (or anything like that, for that matter) would be less scary in some senses because it would likely ignore people and just roam around. It would be impractical, as it would be incapable of gathering hosts, and it would be far too easy to spot and you'd hear it coming from literally miles away.
Of course, that's assuming the damn thing could even move quickly, which it probably couldn't. Something that large wouldn't be able to move very quick at all and would be ultimately easy to escape from.