Yeah, I noticed this as well. I had stopped reading comments for about a year, since I got really busy (nothing to do with the state of the comments), and only recently have been reading it again. The sentiment is different. Lots of people nitpicking at random little things that have nothing to do with the main point of the article.
It's like lots of people are perpetuating the cycle of:
1) Read the title and get offended and then write a snarky comment
1a) Read part of the way and and then write a ranting comment
1b) Read the full thing, but nitpick at something that doesn't have any bearing on the main point.
2) Get upvoted by other trolls
Sad thing is, I think it's chased away some of the better older users like http://news.ycombinator.com/threads?id=edw519 He hasn't posted much in the last half year, and everything he's said was met with negativity.
And of the older users that stayed, their sentiment is pretty negative as well. I'm not sure how this happened, as HN usually self-corrects. But lately, this has been going on for seemingly a while when I read back post comments.
I'm not sure what to do other than post more insightful and positive messages and don't reply to the negative trolls.