When people feel passionately about a topic, many times their posts are more abrupt than I am sure they mean them to be. Although, since we are typing our responses, abruptness could just be the result of our typing skills!
I know that when I am commenting about something near and dear to my heart my opinion is going to be much stronger than a topic in which I might only have a passing interest. I may still want to participate in the discussion but the strength of my convictions will be considerably less. I know that when posters who have never lived in the USA feel that they can negatively comment on our lifestyles or our politics, I take exception. Good or bad, it's my country and I am proud of it, so if someone belittles the life I have here my posts are likely to reflect my frustration with the comments that were made. In the same vain, it would be wrong for me to post something negative about the UK as I have only a "textbook knowledge" of life there.
That's not to say that anyone should be rude. Even at my most frustrated, I try to post with a clear head and think things through before I submit my post. Rudeness is completely counterproductive. For instance, Simon Cowell's Idol comments would be so much more helpful (and excepted) if he toned down the attitude. The contestants might come away with knowledge that could help them with their singing, even if they are voted out of the competition. In the same vain, if you want to get a point across, a well thought out position is going to be much more accepted than a comment liberally sprinkled with offensive language, no matter how many letters are "*" out.
I've said it before and I'll say it again, all we need to do is apply a little common courtesy and a respect for other peoples opinions.
Kaz