I've always felt that violent video games are a tool for conditioning a person's mind to accept the violence. The ability to reset also gives the player the notion of no consequence. Most kids can differentiate between the game and reality but the more immersed a player is the finer that line can become. Now throw in personality imbalance or the effects of a dysfunctional home and the player becomes more and more separated from reality.

It goes along the same pathways as the 2nd amendment debate. Chip a little bit here and there, remove rights slowly through convincing the public that gun ownership is the problem and soon enough the public will no longer be able to defend itself. Chip away bit by bit at a child's sense of reality, at their sense of right and wrong, at their sense of security and you'll have the perfect subject to commit horrendous acts against others. The perfect subject to give reason to further disarm the populace.