Say what you will about other expansions, but Pandaria is quite boring.
Other than raid nights (which are SO fun, I'll give MoP that. The raiding content is very good after last expansion's dismal raiding experience), MoP = Dailies, dailies, more dailies.
Proof of this: My Mage is exalted w/ all Pandaria factions (except Black Prince, obviously) and I find that I have nothing to do but farming for Motes of Harmony every day, and nothing else. I've been doing older content for fun, and it's been band-aiding the problem for the time being, but they really need to add something. Scenarios was going to be it until they made them so dumb; good on paper, horribly executed
This also isn't nostalgia; I joined in early Vanilla and I still think I had the most fun in LK and BC.