I find adults who are uncomfortable around profanity extremely unsettling. Emotions can be extreme (like destroying hours of work because of a git mess-up) language should be able to reflect that.
So it not being necessary is not evidence that part of a language shouldn't be used, or that it isn't easier to communicate with that part of language.
Sometimes curse words help express emotions.
Both are perfectly reasonable to feel uncomfortable around.
If someone where to become annoyed or freaked out because I used the word fuck, or shit in conversation (not in the context of insulting another person; that's a whole different discussion), I would find it very uncomfortable to be around them because I'd be second-guessing my vocabulary constantly. I can be eloquent if I want, but sometimes a "fuck" is justified.
I don't usually like to work with people that are too nice. Its a marker of dishonesty.