HBO, Vulgarity & Character Development

So, swearing if funny, eh? I thought it was just vulgar. Just because something's on HBO (or cable in general) doesn't automatically mean it has to include vulgarity...certainly not just for the sake of it. To be added to a periodic scene because it makes sense within the story? Ok. To allow certain vulgar words to be said by or about a character to help define or add to character development? Ok. But to just constantly have characters swear and use vulgarity just because it's HBO or cable? Nay. What does swearing have to do with "for mature audiences only," anyway?