I do not see any need to pretend they don't exist.
"Pretend" there is slippery. It could mean "affecting ignorance of such a thing," which no one is advocating, or it could mean practicing a social decency of the same sort that well-bred people do when they "pretend" not to have heard someone fart during a memorial service for someone's elderly relative.
Was Tolkien wrong, by the way?
The Lord of the Rings is blemished because Tolkien didn't concoct Orkish obscenities?
I have tried to suggest -- perhaps that's the best one can do -- benefits of forgoing obscenity, swearing, etc. Would someone like to mount an argument for the good that is achieved when an author invents obscenities, etc. for a work of fiction?
To anticipate the first argument -- someone will invoke verisimilitude.
To that I would say, I'm not very impressed, so far, by an author's verbal resourcefulness, if he or she can't convey character without use of offensive language. I've read lots of classic works that conveyed character without use of what may, at the time, have been "unprintable" expressions.
The argument for verisimilitude would go like this:
Verisimilitude is a literary good.
It is so vital for good writing that it outweighs other considerations.
Obscene and profane language are essential for literary verisimilitude.
Therefore, obscene and profane language are good in literature.
To this, I would respond:
Verisimilitude is not necessarily a simple matter of a "slice of life" recording of recognizable bits of demotic speech. How a work shall be made to seem real to the reader depends on a number of things, which might include, say, the effect of weather on characters and groups (often overlooked by fantasy writers), etc.
There are other considerations in writing than just verisimilitude. An author who was not selective in his or her presentation of details, but rather tried to cram in
everything for the sake of "verisimilitude" would produce an unreadable work.
I won't attempt to enumerate all the considerations for good writing, but respect along the lines implied by Hammarskjöld and Tolkien would be one of them.
Thus, I think a reasonable person should be skeptical, at the least, about the use of obscenity and profanity in literature.
But there might be other arguments someone would make for why swearing etc. are good. But if they are not good, why would you want to include them?
To anticipate a second argument: The author may contend that he or she feels a need to include obscene and profane language in order to
express himself or herself.
Perhaps a writer regards writing as a form of therapy. Whatever may be said for this idea, it is not a reason why someone else should read that writing, especially if the reader is not the writer's therapist.
To anticipate a third argument: publishers want abusive language, to sell books. So authors "have to" use it.
So that's the price of your soul, author?