A lot of the people I played with back then don't play anymore -- or we've lost track of each other over years and server switches. Even I've taken a break -- I skipped from Wrath of the Lich King directly to Mists of Pandaria, and I've got to say that taking a break was good for my game. When I came back, I'd forgotten about many of the things than annoyed me and Azeroth seemed fresh and fun... even though the game world had changed enough to leave me feeling baffled now and again.
But what about you, readers? Have you left the game and returned? And if you have, did it help or hurt your gaming enjoyment?