Compare this to the way an English gentleman used to express his anger by saying something understated like, "I'm feeling a bit peevish." The "f-word" conveys a more accurate sense that a person saying it is declaring that he isn't a Victorian gentleman and he isn't just a "bit peevish."
It's another way of saying "I'm extremely irate and disgusted" in fewer words (and without sounding like someone's great-great-grandmother).
But is it still? It's used so casually now that our ears have become deaf to it.
Letting a choice word slip out every now and then is understandable. But to use it as a noun, verb and adjective in everything we say is just lazy.