Over time as a society, we decided there were certain words that had a certain special power and weren’t to be used all the time. They were only to be used out of anger, either anger at something that happened to you or anger directed at something else, such as an insult. If they were used all the time and weren’t “special”, they wouldn’t be an effective thing to use when angry. Personally, I think the idea is somewhat stupid and I know that many words have lost that special power and more words will continue to lose it and I have no problem with that.