Long time player as well. To me without a thriving community no matter what new shinies that get thrown about, you'll eventually hit level cap and be bored. What made WOW fun was interacting with different people not just the guys that stay up for days to get to level cap, but also people like the single mother that works as a bartender, the retired vietnam vet, the guy that's just starting his career in IT, or people that are just graduating from high school trying to figure out what they were going to do in life. The beginning of Cataclysm ran off a lot of people; because, although they were fun to be around, some of the mechanics were brutal which led to people getting left out of dungeon/raid runs.
It would be nice if there was something to do at the "end" of the expansions. The last time I logged on a couple of weeks ago, it was mostly people leveling alts and running content from the expansion before. There's nothing else really to do. Doing the same dailies that you did months ago is not fun and doing Looking for Raid is kind of boring as there's little effort that you need to put into it.