I wouldn't be so quick to say so. Charles Starkweather, Howard Unruh, Carill Fugate, Melvin Collins...and that's just a brief list. True, there weren't as many, but it's not like they didn't exist.
With everything interconnected today by the media, we become aware of anything and (almost) everything in a matter of minutes. Very few things are 'local' anymore, which is why there seems to be a growing epidemic of violent crimes, even though - statistically - all violent crime (murder included) have been on downward trends since the early 90s.
You could make the argument that video games are 'programming' people, true. You could also make the argument that video games serve as a form of catharsis to release aggression.
But I suppose we won't know the true results of what today's popular culture will bring until today's children become older...so, probably not until the 2020s and the 2030s will the consequences be felt.
If something more worrisome (like America defaulting) hasn't occurred by then, that is. But alas.
For what it’s worth:
Suspect In Colo. Theater Massacre Graduated From UC Riverside In 2010
(LOS ANGELES) — CBS2 has confirmed that the suspect in Friday morning’s shooting massacre at an Aurora, Colo., movie theater graduated from UC Riverside.
According to the university’s online alumni directory, James Holmes graduated 2010 with a degree in neuroscience....
...“The University of Colorado Denver|Aschutz Medical Campus can confirm that Mr. James Holmes was in the process of withdrawing from the University of Colorado Denver’s graduate program in neurosciences,” the university said in a statement.....