The launch of MoP had enough new content skillfully created for, to use a baseball analogy, the game to make it to first.
Now 5.1 is revealed, and MoP is going to make it to second.
Not only are there going to be more than just 1 new daily hub, but the "probably won't happen" VP upgrades are slated for addition, pet battles are being updated, and another whole-new feature is being added (brawl clubs).
At the rate Blizz keeps adding new content, MoP may well bring back the Vanilla days of near-constant new things to do.