schmea: I'd just like to say that I disagree with downrepping for no reason other than you disagree with someone's opinion.
This has been stated by others in other ways, but this is the last one I read so I'll reply to it. I totally agree with the sentiment here. Down-repping just because someone dislikes an opinion should be frowned upon. If the tone or purpose (e.g. spam or flame-bait) of a post is offensive to the person in some manner, then I believe down-repping is called for and should be encouraged.
For me, I expect people to believe different things and think in different ways that other people. I expect a fair amount of disagreement on forums. This goes double for an international forum such as this; simple turns of phrase and idioms can even be taken the wrong way if care is not taken. Let's not even get started on folks possibly misinterpreting sarcasm and/or dry humor. I think due care should be taken to avoid such misunderstandings.
Which brings me to my next quote, and next point:
langurmonkey: My point is, sometimes you have to offend people to say what you want to say, properly.
I totally disagree with this sentiment. I think it is totally possible to argue the opposite side of a point without offending someone else. Just because someone disagrees with someone else, it doesn't automatically follow that they have to dislike that person or go after them personally. The biggest mistake I see on forums is to go after the person rather than the argument. This is when threads usually start to get heated.
There can be civil disagreements, and I think a reputation, when used properly, greatly aids this by subtly letting folks know when they have stepped out of line or have made a good point.