If we had half the otaku games in Japan for the PS3 and 360 then this whole issue would be much more black and white. By otaku, I mean filthy Japanese Hentai games where the goal of the game is to have sex with or rape a woman/girl.
Seeing as how those otaku games stay in Japan, we can only comment on the violent nature of games and whether 2 year olds will be harmed by playing Postal or Grand Theft Auto.
My take is that GameStop, Wal-Mart, Target, and any store who sells video games with an 18 ESRB should be held to the same standard as a liquor store selling alcohol to minors. Yes, they will most likely not die from consumption or get into a car wreck. However, some do thus to protect the minority who cannot differentiate reality from fantasy because of neglectful parents or their dad having weak sperm, we should fine GameStop stores just like police departments fine liquor stores for selling liquor to minors.
This raises the question, "Do violent video games have a harmful effect on children?" I would guess no for the vast majority of children. However, just like the minor illicitly buying alcohol and consuming it, we have certain laws in place not only to protect the "vast majority," but to also protect the minority who due to bad parents and/or bad genes (polite way of saying someone has a low IQ and is borderline retarded), we need to hold mature video game content to the same standard as we do with alcohol and minors.
I am not innocent here. I watched "Maximum Overdrive" before age 5 at my babysitter's house and played Doom and Duke Nuke'em 3D before the age of 14. That being said, I rented out every Disney and SNES game for rental in Blockbuster regardless of review score.
The difference now is movie rental stores have their video game rental shelves full of mature games. Back in my day, you would be hard pressed to find the majority of SNES rental titles as 18 plus. Nowdays, looking at Blockbuster's 360 rental shelves, I see a majority of mature content games and not enough kid friendly games. Same applies for PS3, but not the Wii.
I am not arguing from a position of strength here as I am a hypocrite regarding this issue. My concern is not for the vast majority of kids who can play, watch and listen to whatever and turn out normal, upstanding citizens in their society. Who I am concerned for are those kids because of a lack of nurture and or a bad nature, just cannot differentiate between fantasy and reality causing them to learn society is just like the video game and behave in such a way that it not only destroys their life but other innocent lives as well. If the evidence shows I am wrong, then please enlighten me and I will throw this belief of mine out.