The reason cunt is offensive is not that the anatomical cunt is a terrible thing, but rather that anything sexual could not be discussed in polite society for several hundred years. Therefore, saying 'cunt' marked you out as someone who was not part of polite society, something that the middle classes would try to avoid at all costs. As men were basically in charge, and they had penises which they acknowledged, the cock did not become so offensive (although a word for the sexual act did).
As the formal class structure became more fluid in the 20th century, the use of the word increased, although the bourgeois aversion to it remained (and, I have seen it suggested, possibly received a boost from the presence of North American servicemen in Britain during WW2, as the usage is much more gendered in the US and Canada).
So basically, I tend to think of people who have a specific aversion to the word 'cunt' as being Hyacinth Bucket types who are overly concerned that no-one will think they are common. The fact that a couple of them have popped up on this thread to mention that they do consider people who say cunt to be common, or think that it demonstrates that they have a poor vocabulary, bolsters my position on this.
I am generally very pro-swearing. It's fucking great.