Board Thread:Movie Discussions/@comment-27637441-20160128232821/@comment-25285745-20160203014352

Again, the simple answer is because the film wasn't written that way. It doesn't have to make logical sense within the film's universe. It's just how the movie was written. It's for plot purposes.

People could speculate about why the Guardian Monsters weren't awakened in 1954, but none of that really matters in the long run. The film was written the way it was so that it could tell the story it wanted to.