The problem with this argument I believe is that people who believe video games enforce negative stereotypes also believe that people are born good, which in many cases just isn't true.
Generally people who are influenced by games are stupid and have no real morals. They see it in a game and find "fun" in it. So their logic tells them that if it's fun in a game it's fun in reality. And since my character doesn't feel remorse for these innocents I've slaughtered, why should I?
Which is a very good example of a a Psyhopath
Wikipedia said:
Lack of a conscience in conjunction with a weak ability to defer gratification and/or control aggressive desires, often leads to antisocial behaviors. Psychopathy does not necessarily lead itself to criminal and violent behavior. Instead, psychopaths high in social cognition may be able to redirect their antisocial desires in a different, non-criminal manner.
In games I often go on hour long killing sprees while laughing evilly the entire time. In GTA Vice City I spent 3 hours in a tank going around the place killing people at random.
In Fable 2 I slaughtered Bowerstone for some 2 hours to farm gold since I got the Augment that gives me gold/kill and one shotting Villagers for 11 gold was sexy.
Does this mean that I'll go hijack a tank and terrorize Miami, Or Kill an entire town for money? No, because unlike these kids who play GTA and decide to steal a car or shot someone I have two thing they don't, A conscience and a hefty amount of intelligence.