This is a gradual change that has happened in all MMO communities, you can't get away from it no matter where you go. I attribute it to design changing from relying on each other to reach the end and the rise of solo content. Not that I don't like solo content, I like both designs, but solo content means people don't have to learn to play well with others to get to the end. In EQ1 and FFXI, you pretty much did.