I think in this context, and really in any context regarding language, its important to language is an ever-evolving creature. The English we speak today sounds nothing like it did centuries ago, and I imagine back then there were purists who had great disdain for people who popularized the slang of the middle ages. Many of these words become common words used today by even the most proper of people.
I think its a little naive to think that language is static and changes won't happen. Yes, words that were considered vulgar 50 or even 20 years ago are now used freely on network tv (I've started to hear 'd*ck' on tv like nobody's business), but I think its reflective of a world in which technology forces changes to happen much more quickly and uniformly. As its been pointed out, though, words like 'bitch' have been effectively neutralized due to their common usage. I'm guessing we look back 200 years from now and 'bitch' and the s-word and the f-word will seem common and mundane and will have effectively been neutralized by their overusage.