The article (yeah, I did RTFA) points out that those games are rated for age 17+, so I don't see what the issue is.
I wouldn't want my kids playing COD-MW2 or L4D2, but to be honest, they wouldn't want to play them anyway - they'd be much happier with the latest cutesy Wii party game, or something for the DS involving ponies.
Yet again, the mainstream media make the assumption that all games are for kids and are therefore completely shocked to see that some games involve blood, gore and subversive naughtiness.
Actually, I don't think they're shocked at all. They just think that their readers will be, and that's what sells papers and generates click revenue.