Because one of the luxuries of conducting discourse by post is that you have time to choose words that are more suited for your specific intention. When speaking, saying "fucking" is often simply a replacement for "uhh". At least, it is for me.

How a sentence with swearing is perceived is wildly unpredictable. For example, "science: it works bitches" was a comic and tshirt by Randall Munroe. Not for a second when he wrote that did the sexist interpretation of "ladies, start trusting science" enter his head. I'm not saying that is a lesson in not swearing. I'm just saying swears tend to have loads of meanings, and they are hard to use unambiguously. In art, ambiguity is often key though. I am against censorship.