Yep. If it were a simple case of "The voices made me do it!" then we'd be having a different discussion. And a lot less frequently. After all, these mass shootings have increased in frequency even as gun ownership has decreased. Back in the 70's, half of Americans owned firearms, and there was quite a lot less fuss about it. Now we're down to something like 30%, with widespread informational campaigns on proper safety and security...and yet the shootings have become more frequent.
The media frenzy has got to be a tremendous factor.