I don't know what would cause such a change, but maybe it's one of those situations in which the medium is the message?

I mean, magazines like DDI and sites like this one (and MF as well) tend to create a feeling that you're part of a community of sorts.

But on Twitter, everyone is sort of atomized, everyone is just another face in the crowd. And people tend to be pretty nasty there.

Just to underscore the point, we don't know each other, but here we are, having a conversation -- it's something that makes sense here, but which would seem strange on Twitter, where I would just be a random guy replying to your tweets.