One thing I really like about online forums is that you can really speak your mind. I, like the OP was very sensitive when I first started posting online, but now I just don't get offended anymore. I generally try to avoid controversial topics because no one ever convinces anyone to change their mind on internet forums, but occasionally I get drawn in, even on the MMM forums. :P
In person, I'm overly cautious about what I say so as not to offend, and I'm also not so articulate compared to my writing. I really like the ability to think carefully about what you're saying in online writing. With that being said, I also do value in-person communication (we have a local MMM meetup in a couple weeks, after all!). :)
I do think it's good that people feel more comfortable arguing online. I wish people were better about speaking their mind in real life. And I think part of that might be associating disagreement with abrasive speech. So I think it's good practice to strive for pleasantness in online arguments. But, yeah, there's definitely a different style in online speech that's more direct, so I generally err on the side of assuming people are trying to be direct rather than rude.
(I actually have the somewhat opposite problem which is that verbally, in real life, I come across as charming and can get away with saying all sorts of shit that, in print, sounds more combative.)
Personally, I post on the internet because I'm interested in what people's responses will be to it. I don't just post to hear myself type.
Actually, posting in the internet can be very similar to journaling - very therapeutic. I also really enjoy what other people have to say and love learning from them, but at the same time posting your own thought processes in a comprehensive form can really allow you to check your thinking and make sure it is logical.
Sure, if no one responds directly to your post (which is true of most), you still benefited from the exercise of spelling your thoughts out to an imagined audience.
But there are those people IRL who talk just to think out loud...and they end up not adding much to the conversation :) So I try to be sensitive enough not to be "that guy."
Plus if I'm journaling, things get spelled out comprehensively, but there's a lot of mental shorthand and personal references, so I figure making sure my ideas would be clear to others is a form of consideration.
If you suspect you are being insensitive you probably are.
Ha, my observation has often been the opposite. It's like Alzheimer's. If you're worried you have it, you probably don't, because having it means you've lost the faculty to notice what you're missing.
Ultimately you shouldn't care what anyone else thinks.
The pendulum swings back and forth on this one and at the moment it's a trendy thing to say. I would happily encourage anyone not to live their lives according to what everyone else thinks, but don't see a need to go to the opposite extreme which is at this point being extolled as a quasi-religious virtue. It's as though having the least concern for others has become as terrible a sin as coveting your neighbor's wife used to be. I think it's complicated and difficult to process that we can do things just for the sake of others but still be responsible for our choices. But I have faith that people can comprehend ideas even if they don't fit on a t-shirt.