Yeah, the rudeness factor does seem to be going up a little. And I'm not talking about people not saying "gl hf" or "gg", because everyone forgets to do that once in awhile.
A couple of weeks ago, someone beat me on isotropic and then posted something like, "That was too easy. A Fairgrounds strategy? Really? That was stupid." That ticked me off a little. When someone loses and posts a snarky remark, it doesn't typically bother me, because I've done it too (I'm not proud of it, but I have). I find my anger in such situations is really directed at myself for having a poor strategy, not at my opponent. As a rule, I try to avoid personal attacks, and I would like to see others do the same.
We all know that the internet is somewhat anonymous, and therefore people tend to be themselves more than they would in real life. If someone would be polite in person for selfish reasons only, he probably won't bother to be polite online. I feel compelled to remind these people of something Joss Whedon once said - "Always be yourself...unless you suck."