Swearing or using expletives is a cultural thing. Usually it comes down to the view that using certain terminology is vulgar and shows a lack of ettiquette and social refinement. Granted a lot of upper class snobs have deep seated family issues, but this is about the mask that people present, rather than anything of merit.

If you swear it's okay. I swear sometimes, and I don't really care. You might also want to watch Penn & Teller's bull as they have an episode on swearing.