As a writer myself I've often found the opposite is true of published fiction. (Opposite of Mouse's comments, that is.)
Very few people in a novel "speak" like normal people on the street. There are phrases and variations you can use in text that sound horrible when spoken aloud. Very often when you get "bad" dialogue in a movie, it wouldn't cause a batted lash in a novel.
By that same token cursing often, while realistic, is somehow jarring in text. Perhaps this is because text is static. When a word is spoken, it is gone, air, released and that word is no more. A word on a page exists in large part forever, and stays within your line of sight for a long time. It sticks, it stops, it says: "Here I am, that's right, I said ****. ****. Right here."
Character-wise I seem to get the point when an author says: "______ let out a string of epithets that made even Flexor The Mighty red faced and uncomfortable." As opposed to: "You ****, I'll **** you and your ****ing sister right in the **** ****." It loses something. A character can seem very adult, if coarse and ill spirited if he "releases curses so foul the air became thick" but if the cursing actually begins he no longer seems coarse, just ... juvenile.
I'm looking at my bookshelf right now and I can't easily call to mind a genre novel in which the author or a character regularly uses curse words.
There is also the fact that curse words are a very grounding, human, HERE sort of thing. They disrupt the verisimilitude of a world ... do goblins use the same words? The same way? With the same foul innuendos?
Not burning your britches personally, I'm just disagreeing with the idea that it "feels" realistic to use Old High Crass in fiction, especially genre fiction. Moreso than any other form of fiction, genre fiction is the place you come across those words most infrequently.
--HT