Oh goodness, another one of those "tell me your stuff" threads. ;P
Back when I first played on this server, there weren't many people playing in the main server. I usually like playing with small, tight-knit communities, so it didn't matter much with small player counts (even if some of us had to seed the server). But now the community has grown ever since, so there's one less motivation to stick around.
It isn't really anyone's fault; I'm just more inclined towards smaller groups. That's probably why you'll never see me at PAX.