Society viewed language with swearing and other such colorful metaphors to be a true sign of an irrational and barbaric mindset.
of course by the 1980s this had changed as James T. Kirk observed to Spock:
Spock: Your use of language has altered since our arrival. It is currently laced with, shall we say, more colorful metaphors, "double dumbass on you" and so forth.
Kirk: Oh, you mean the profanity?
Spock: Yes.
Kirk: Well that's simply the way they talk here. Nobody pays any attention to you unless you swear every other word.