I had actually left the game shortly before LK's release due to the idiot-factor. However, I was drawn back in by LK and switched servers ... it's remarkable what a change like that can do.
In my case, a lot of that has to do with the fact that the server I moved to (Silver Hand) is an RP server -- even though there's very little RP these days, the general attitude is a bit better than I've found in previous servers. There's generally a bit (okay, a lot) more acceptance of different ways of playing the game other than just the top-end PvP/PvE.
And at the top-end, the presence of
Leftovers makes a huge impact as well. When you've got a community of thousands with the general attitude of "we'll all here to have fun" making up the majority of the server's raid groups, it makes a difference. There are still idiots (both in LO and on the server), but it's nothing like I'd experienced previously.
I wouldn't still be playing if I hadn't swapped servers and made all the friends I have. Even progression raiding has the feeling of hanging out with friends -- something that's pretty rare in my experience.