The idea of flanking for extra damage is pretty neat. They've tried to add this to the game before (Flanking Strategist).

The problem is that in BGs, you get a lot of players (primarily NBs) who just hang out and wait for a very long time before they decide that the time is right to burst an opponent. The desire to look for a flank will make them wait even longer, as it'll reduce their engage opportunities. Imagine the number of NBs that will stay in stealth until they can get the perfect flank. This is not healthy for BGs.

One positive point in regard to this change is that it encourages melee engagements, whereas the current Camo Hunter strongly encourages ranged engagements.