I've always had my one "main", but I did get a ton of alts leveled during Mists. I find myself less of an "alt-aholic" these days, primarily because I didn't want to manage so many ring quests and garrisons in Warlords.
With the Artifacts and Class Orders in Legion, I can easily see myself becoming obsessed again with maxing every one of my alts just to experience all of the stories. :P