I think every generation has new things which are suspect to the parents cause they just don't know and/or understand what the 'pull' is.
I understand the addiction of the computer. I have a problem with it as many do -- time loses its reality when I step into the computer world. Based on this, I can understand how kids can make gamining the focus and center of their world. I'm not sure I buy into the games causing violent behavior (as I did not believe that movies did so either).
I've been playing them for over........well, since pong! I've never shot, hurt maimed or in any way harmed another human being. Living or Zombied. Thats what the games are for! muahahahahaha!
Seriously, parents need to keep a certain amount of interaction with their kids. Play games WITH them if need be.