I think swears are needed, because I imagine people would causally swear in a world darker and more dangerous than our own.
If I'm ambushed by goblins, I'm not going to go 'Oh bother!' like some blood-spattered Winnie The Pooh.
..I'm playing a Warlock, so I might say 'By the the three prehensile balls of <insert my Great Old One Patron's name>!'
But normal swear words work better. Also:
The f-word is of Germanic origin, related to Dutch, German, and Swedish words for “to strike” and “to move back and forth.” It first appears, though, only in the 16th century, in a manuscript of the Latin orator Cicero
