personally i believe the solution would be to tweak the BG's percentage rather than allowing it to drop from WG, here's why:
1st: WG is done only few times a day, which means drop rates would have to be significant, otherwise it would be a completely inneficient way to "farm" the scrolls, and if it had high drop rates everyone would give up other BG's in order to farm scrolls only on WG.
2nd: WG reward is VOA, and thats why you fight for. fighting for scrolls would place way too much power in a single battleground.
3rd: you already have multiboxers camping almost every single WG battle without the scrolls, imagine what would happen if you add them, WG would be completely unplayable unless you were a multiboxer yourself.
4th: we should also remember that transmog is a warmane feature and not a retail one for wotlk, so we cant actually "demand" high drop rates, thats what they are also sold at the shop.