Very, very good discussion on this thread so far folks! The like of which make this board great!
Personally, I don't know if there are any right answers as to why someone goes off his/her rocker and kills just to do so. The OP made some very good points which are spot on in my opinion. Humans will be humans after all. So much of the world, warts and all, is now right in front of us 24/7 unlike any other time in our history.
We learn behavior early and societally we have been pushing out at the boundaries that make a civilization civil in so many ways. This doesn't happen in a vacuum and the young are being shortchanged and altered in ways we abhor, but can't seem to get away from.
We are now in the information age and just getting a grip on the scope of how that will play out. So far, it's brought unbelievable advances, but do we really know the scope of how it will effect our species and ultimately alter our humanity?
Think about how you grew up and how that makes you who you are today. Then think about how today's kids are growing up and ask what they will become when our age? Nothing more or less than what we made them to be? I think so.