When I apologize, it's usually for one of 3 reasons:
1) I sincerely think I've done wrong and I feel obligated to be honest about it.
2) I'm attempting to diffuse a confrontation because I don't think the other person can handle it.
3) I'm attempting to diffuse a confrontation because the other person is boring me and I'd just like them to shut up.
I don't do #3 very often--more likely I'll just drop the subject without further comment.
Many times I do believe I've done wrong and, as I expect other people to own up to their mistakes, I demand the same of myself.
Sometimes I think that the person is more important than the topic at hand, or than my expression of feelings on the topic. Many people are hurting pretty badly, and truth doesn't *have* to be expressed with all the sensitivity of a jackhammer. If my opinion on something is very important, and the person signals that they aren't able to handle my opinion in the manner I've expressed it, then I'll attempt to back up, repair the damages, and express that opinion in a more useful fashion.
At that point, my apologies have to do with being the bigger person and not demanding that they take steps they claim they are not able to handle. Maybe they could handle those steps, but it's not my job to force them to. If it's someone I know quite well, I can better determine when they are able to take those steps. Online, I really hardly know anyone so I think it's safer not to risk causing people more pain than they already face.
And, substitute, I agree with targo about "the world" seeming to scorn sensitivity. I think most of us--whoever we are and whatever type--feel we've been scorned for being who we are. The fact is that people tend to say negative things more quickly than positive ones. The person who berates you for lacking sensitivity is unlikely to tell targo what a wonderfully sensitive person she is. And the one who scolds targo for being too sensitive is unlikely to show open admiration for your bluntness and straightforward honesty. Unfortunately, it's the negative that more often gets voiced.