I am not an experienced gamer and am a fairly new wow player, and I can't really understand how it is broken, I am not questioning you per se, but if I really enjoy something how is it broken?
Be gentle
I think when someone calls pvp broken it has nothing to do with BGs. World PVP is non existent because there is no reason to do it, sure you can get a few good small scale battles going on here and there if everything happens the right way but in reality there should be a lot more wars raging between horde and alliance since we aren't supposed to like each other yet almost every zone has 1 of each sides city in it. But the only benefit to pvp is the gear and the only way to get that is to mindlessly farm BGs.
Another issue in PvP is that not all classes are viable and not all specs are viable.
There are more issues with simple game play and over powered classes. I remember when Warlocks could not be killed, Druids pwned and shadow priests were the bane of most peoples existence.
Classes in WoW are balanced for PvE Raiding and the effects in PvP were often over looked causing extreme imbalances.
I also agree with Where. In the original game info it seemed that alliance and horde would be weekly raiding each others capitals. That simply does not happen unless it is a map exploit.