It even goes beyond the 'heavy rock' of that time. TV airings of Elvis' performances used to be limited to the top half of his body, because his gyrations were deemed too sexy for TV. Look at TV now.
It's true, it's all about the generations. Like many people have said, once the older generation fades out, our generation of people who grew up with videogames will be the norm.
Nintendo seems to be accellerating this now. Games are bleeding in to the older generations already, softening it up. There are still the random negative spikes, like the recent Manhunt 'banning', but as a whole games are entering 'mainstream' entertainment.