I think they only ported everything as they were in Lordaeron (in which the pve contents are buffed) and just fixed for crashes and thats it, as you can see the mobs of old Stockades (pre-cata) and the new Stockades overlap, and we had to wait for more than a year for that content
And sure we could use more BGs, it gets boring doing Arathi and small Arathi (Gilneas), Warsong Gulch and large Warsong Gulch(Twin Peaks) and the child of arathi and warsong gulch (EotS) over and over, with a rare AV here and there, but I think BGs with vehicles must be a pain in the *** to code, and as cata is not their priority now we better dont get our hopes up