Every time some deranged asshole flies a plane into a building or shoots his classmates/coworkers, we hear from the television and the mouths of the elderly that the world is spiraling uncontrollably towards the endtimes. Crazy is nothing new though, and these people have short memories. If you think people committing horrific acts of violence on innocent bystanders is just now coming into vogue, check out this lunatic and what he did- in 1927.
I'm a little suprised there has never been a film made about or inspired by this, though given the supreme awfulness of what happened I suppose there wouldn't be an appropriate way to handle it.
Another possibilty is that media of the day, or at least the people involved, were unwilling to sensationalize or even talk about what happened. Crazy always been crazy, but it would seem that in the present day, sane is way more willing to watch.