The offensiveness of many comes from the original intention of the word, which was generally some sort of a condemnation of another person (or perhaps sometimes some other taboo). To repeat it is to repeat some of that original intent, at least at times... But I think now a simple "fuck" has all but lost that meaning, and I would say it's not really inherently offensive. And well placed, sparingly used, it can be a good way to extend your range of emotional expression. Well, as long as it's not at cost of everything else.