The purpose of profanity is to express strong emotion. It should be used sparingly, like a spice, lest it become monotonous and lose its flavor and impact. As one who enjoys putting words together, I'm bothered by people whose conversation is little more than one long stream of obscenities. If all you're going to taste is pepper, why bother putting anything else in the stew?
However, I'm equally offended by prudish types who take offense at the slightest curse and attempt to censor others. If all you want on your plate is a colorless, flavorless gruel, that's your affair, but don't you dare try to dictate my verbal cuisine. Excessive use of profanity may indicate a lack of imagination and an undernourished vocabulary, as has been said, but sometimes f*** is the appropriate word.