I've noticed it also. When I first joined people really took care that their comments were thoughtful and respectful, even if they were disagreeing. Is there anything to do other than to personally try harder to be thoughtful contributors?
Those comments are still there, just a bit less obvious.
I figure it is because the "original" members were of a certain level of contributor. "hand picked" in a sense (classic early adopters). A these move on to pastures new and a large numbers of new people come in you start to get a range of commentary style rather than just top class stuff.
(not that all newcomers are bad - or indeed not that many of us are - just that you get a range of attitude).
And of course almost outright trolling is less obvious once the general range of commentary style is expanded; so it passes off as serious discussion.
