Expletives communicate a lot of emotion.

"I ran like expletive down the hill" communicates something different than "I swiftly ran down the hill" even if the expletive adds no additional facts to the narrative.

In some ways, expletives are among the most communicative and interactive words around. They're nouns AND verbs, they're both repulsive and engaging, they're simultaneously shibboleths and among the most common of words.