Why swear? Why not?
A long time ago, in my college days, a co-worker at the UPS truck wash came up to me out of nowhere and demanded to know "Howcome you never cuss??" I didn't have time to carefully think through an answer, so I just said, "Because I don't need to. Most of the people I know who cuss a whole lot have really limited vocabularies and no imagination."
Since then I've taken the time to think it through more carefully, and I realize now that beyond the question of vocabulary and imagination, most use of swear words is simple verbal aggression. A type-A guy who thinks he's tough, or who thinks he needs to be tough, will swear a lot mostly to establish his ascendancy over his immediate audience. Others around him will swear in order not to be thought less than manly. (Or less than equal to a man, as the case may be).
It's something like taking up smoking, which is still common but used to be almost universal. Kids were eager to smoke because it made them appear to be more grown-up. They used rough language then, and do so even more now, for the same reason.
I would agree with JohnRobison. How many will object if you put the words in, and how many will object if you leave them out? I would also add the question whether you, as an author, want to encourage young people to use even more cheap, contentless swear words as ordinary punctuation marks, or would you prefer to help hold the line against that rising tide of coarseness?
Nathanael