While it's true that swearing is no more than a social taboo, that doesn't mean that treating it as such (and respecting it as such) isn't important. Afterall, even murder is just another social taboo.
While swearing might not be quite as destructive as murder, it can be very destructive to people, which is why it's a taboo. Sort of a 'treat others as you'd like to be treated' mentality.
Common swear words have many meanings and uses within different social references. Some swear words are much more offensive than others. Racial slurs, for example, are used soley for the intent to insult another person on the most personal level. Some find these words are ust as damaging to the mind and self as a physical blow, as many of these words represent tens and hundreds of years of pain, humiliation, and real, physical abuse. Anyone that says mental and emotional abuse from words isn't real, or isn't as damaging, really needs to learn a lot more about it.
The old adage "sticks and stones," while great in theory, doesn't really hold up as well in real world situations where words really can hurt.
The word n***er is actually derived from the Latin word niger, meaning black. This is probably the most common racial slur we all know, and while it is often used affectionately within a particular group of people, even that usage is often frowned upon by others within that same group.
Common swear words aren't as taboo as racial slurs, and are more openly accepted within society, depending on the usage. There are many ways to use swear words and they're generally all acceptable within their proper social construct. When used for emphasis, exclamation, humor, I think they're okay. But when used as an insult, like slurs, they become taboo and unacceptable again. This is why it's forwned upon when children swear: they often use such words without any realization of proper context. A young child running along, tripping and faceplanting and getting up and saying "sh*t!" would be funny because of its proper use as an exclamation of surprise. The same young child's use of the word to call another young child "a little sh*t," while funny in theory, would be offensive and abusive to the other child and that child's parents.
The word crap, which I've never heard referred to as a swear word, comes from Thomas Crapper who popularized the modern toilet. He didn't invent it, but he did heavily market it and was primarily responsible for its popularity (though it probably would have happened anyway). He did invent the ballcock, which is the device inside the toilet tank that prevents it from overflowing when refilling with water.
