I see your point but surely a kid seeing Animal Rescue or something on NatGeo Wild (both on early evening) is going to be more traumatised as the starved dog tries to walk across the room or the tiger has a nice chunk of Bambi's leg rather than seeing some CGI bloke firing a gun into the air?

Also, I'd imagine the adverts would be targetted to certain shows so an advert wouldn't appear in an episode for Heartbeat, for example, because the audience isn't going to form a likely user base of a violent video game. Therefore, the kid (or easily offended person) is only likely to see the advert if they are watching a show with a reasonable level of adult content anyway.

As for sex and nudity appearing in TV shows, who cares as long as it's mentioned before the show starts? Channel 4 seems to have tits on show from 8pm these days and pretty much anything after 9pm!