A new study has confirmed something you already knew: That swearing can improve a person's tolerance to pain. Specifically, people are able to submerge their hands in freezing-cold water longer if able to let go of a few good ones than if they're only able to use more neutral words.
One aspect of swearing that the article touches upon is its universality, something easily attested to by anyone who has tried to learn another language or experienced any type of cultural-linguistic exchange, either aboard or right here in the U.S. -- swear words are often the first words that a new speaker of another language learns, and they're often great insights into a culture. As evidence, look at the way Paz breaks down the term hijo de la chingada in Mexico, and connects it to the region's history and the crimes of Spanish conquistadors in The Labyrinth of Solitude.
As long as I can remember, I've never agreed with the line that the use of swear words betrays a limited or weak vocabulary. Their artful use has its place in speech for emphasis and can often add color to what might otherwise be dull.
If some four letter phraseology helps someone relieve stress, it seems like a much more appropriate (and victimless!) way of handling it than, say, the placing of a fist through a wall, or into someone else.