Well, The problem is that Paladins (most noticeably in PvP) are quite possibly the hardest of any class to kill. But in the same respect, they deal the least amount of damage in return.
Paladins are forces to be reckoned with, in a party, they shine the best when they make the other players look good. With all manner of blessings, auras, heals, cleanses, etc. Horde right now especially in BGs, seem to be a LOT more team-oriented, and Paladins will make an excellent addition to their ranks.
Alliance, (at least from my opinion and experience) Seem to usually fall short in the damage catergory of PvP. With an excessive amount of Priests, Druids and Paladins already, adding Shaman to the mix will effectively boost our Damage dealing capabilities quite a bit, and will make the playing field a LOT more even in the 20-29 BGs with both sides having access to Ghost Wolf.
All in all, i welcome the change. And you'll be seeing my Big blue ass running around on Uldaman in no time.