While I enjoyed "city raids" in Warhammer Online, it did get annoying from time to time because of faction imbalance (Order vs. Destruction). I'm figuring with Guild Wars 2 you just need to give them time and put in suggestions asking them to add these as either DE's or maybe a Battleground type area.
I'm happy with the current system, especially since we haven't even seen much of it yet but small tastes.