The World of Warcraft Annual Pass was a limited-time offer that required a commitment to subscribe to WoW for one year, first made available on October 21, 2011, the opening day of BlizzCon 2011, and ending on April 30, 2012. Doing so rewarded players with the following:
[Tyrael's Charger]
Free digital copy of Diablo III
Guaranteed access to the World of Warcraft: Mists of Pandaria beta.
Requirements
https://wow.gamepedia.com/Annual_Pass
MOP release : Initial release date: September 25, 2012
So yes, it was to keep people during Catashit