I don't believe profanity is necessary to communicate but I still use it time to time to stress a point or to make someone mad. For instance I will roll down the window and say "Where did you learn to f*cking drive?" when I am agitated. I'm not about to ask them in a polite tone of voice "Excuse me, but where did you partake in drivers education classes?" It wouldn't have the same impact that I am trying to get across. So profanity might not be for everyone but it does have its uses from time to time.
I also agree with Watch. If you are around people that use it all the time you are a lot more prone to using it yourself because you do become a product of your environment to a certain extent. You might even swear and not realize it like the guy on Fatty's softball league.
I don't use it on a regular basis because I do think it stereotypes the user as being non-intelligent and I don't want that image for myself. I just pull it out for those "ohh so sweet" moments.