My experience is that we all seek scapegoats; rock music, metal, sex, lack of prayer in schools, Dungeons and Dragons, video games… basically whatever the youngest generation is into that the older folks weren’t becomes EVIL and is targeted as the cause of all murders, rapes, wars, cancer, tooth decay, and excessive flatulence. There are kids that go on shooting sprees without playing games like this too. In fact, it used to happen before video games were even invented! There are plenty of things out there in the world that are far worse than games like GTA. Just turn on the evening news.
As for it not being healthy for young minds, if your kid can’t tell games from reality then somebody did a shitty job as a parent. It’s just a game! I find such games a nice release. Like many guys, I am naturally aggressive and I find that random violence with no consequences helps blow off steam without risking prison time.