A) Violence in movies can be just as bad. And it's not something I completely condone either.
B) Media (TV, film, web) is a passive media. You watch and absorb, your mind shuts off. In video games you're an active participant in the violence you're creating.
I remember last year I was at a Christmas exhibit back near my home town. They had a small collection of old toys. I remember looking at them and noticing they were just a little more than metal with paint. Nothing shot sparks, no glowing eyes, and hardly any moving parts. In order to play with those toys you had to exercise your imagination. Use your brain to play. I worry for today's children and the effect that all of the over-stimulation and adult themed media is having on them. In film school I had a professor who once told our production class to be wary of what we want to put into this world because it will manifest itself. The more violent content we create the more violence we propagate in our society. As Gandhi said, "Be the change you want to see in the world." I think the entertainment industry at large needs to take a good hard look at itself, and be a little bit more responsible with the "art" they are supplying our society with.