The signal from the future we're receiving on our TVs and devices has already been translated by their universal translators into our primitive 21st century lingo so we can comprehend it, including the jargon and expletives. No one speaks Federationese yet. (Remember "Dominionese" from DS9?)But in Star Trek the voyage home they went on about the "colorful" language if the 28tg century. Language changes overtime. Even in a few decades. Roddenberry got it right when he left out most 20th century jargon. Imagine if Kirk on TOS said "we just finished a mission. Pretty damn cool man. " that would have sounded out of place. Niw they say things like "piss off" and "f off." Sorry but the earlier shows got it right when they changed the style of language a bit. Will it really be that way in the 23td century? Who knows but I'm a future setting story it's pretty cool when they go through the trouble to kind of address changing language.

Trek's been doing this since the beginning, as others have pointed out.