In a thread started by quitting player whose final rants include issues such as class balance and the limited number of Battlegrounds, Drysc responds with a rare, long explanation. He mentions that Blizzard understands that not all classes and specs are as viable in PvP, particularly in the extremely competitive Arena environment, and concedes that they are trying to make at least all classes contributive in some way. Protection Warriors, for example, should be able to jump into Battlegrounds or Arenas and "be able to do something with some small amount of success." The 'small amount' comes from the fact that he also unequivocally states that it is Blizzard's philosophy that they have to be ok with all specs not being as viable as others.
He also explains that the dearth of new Battlegrounds or Battleground maps is not due to queue times (they have little to do with each other), but that each Battleground requires a fair amount of work on Blizzard's end and that most of their developmental focus lies in the expansion Wrath of the Lich King. He says that playtesting, balancing, and other efforts are extremely labor intensive. Oddly, Drysc mentions Warsong Gulch, the smallest of all the Battlegrounds, has "terrain issues here and there." Hopefully this isn't indicative of what Blizzard sees as the problems with WSG, as the game suffers from more than just some terrain issues. It's a good thing that Patch 2.4 promises changes to WSG, but it's even better that Drysc has been more vocal on the forums as of late.