This is a really well reasoned thread and I think it's a discussion that is really beneficial. As @junpei has stated comments are typically a binary black/white, love/hate statement.
My personal feelings on it come down to the nature of internet communication, it's about people stating their opinion directly and addressing points on a, well, point by point nature. It's a factor of the communication from forums to Facebook posts to Twitter replies to anything really. I feel this is one facet of the issue in that people feel the need to address all points of contention in a single reply, there is no discourse, discussion or time to consider. It's easy to take a single point or quote and focus on that for a reply without any immediate discourse. There is no real back and forth to facilitate a rational discussion in this regard.
This in itself can be dealt with and isn't necessarily a stopping block for reasoned debate but the nature of such an echo chamber has almost necessitated a desire to be heard and thus the loudest or most noticeable voices get traction, and as is the way, the louder and more virulent voices obtain the focus.
I'm not really sure what can be done to curtail the trend of social feedback, but I don't think a change will come easily. It will be painful and jarring. I sincerely hope we're on the first step of this cultural change right now.