You know, the principal reason that forum software offers censoring tools (whether the blackouts that Discourse applies, or the word substitutions that phpbb did) is because users feel obliged (entitled?) to push the envelope... to see just "what they can get away with." No matter where your administrators try to draw a line, some users will want to go "just a bit farther" - and some will want to go much farther, of course. Self policing doesn't work, and without rules (and enforcement), LCD rules. (That' s not Liquid Crystal Display, kids!)
In my opinion, DurhamBull nailed it:
Fortunately English is a big, messy language so we have lots of choices.
There are almost always better word options than the few that we all know will set some peoples' teeth on edge. Most of us have enough of a command of English vocabulary that we are aware of these better word options. So it seems to me that when those few words are invoked, it's because somebody wants to provoke somebody else, or at a minimum, is indifferent to others' sensibilities.
Which is not to say that, once in a while, the expletive isn't the better (or even necessary) choice - because of its shock value, because the purpose of something is specifically to provoke. But that only works if it's rare; if the expletive is one of your go-to adjectives/adverbs/nouns/verbs... it doesn't shock, it just defines you as crude.
Bottom line, for me? I would love to just disable the censoring function, and be confident that there would not be a race (or a gradual slide) to the rhetorical bottom. But posters keep triggering the blackouts (albeit fairly rarely now), and writing things that they expect to see censored. That's not confidence building.