I think that Blizzard should put in some type of party reward system for doing world events. Like you can get Gold or tokens for special items by completing said events. I know it sounds a lot like Rift. But you just gotta have a reason for people to be out and about the world for you to be able to engage them in World PvP. Quests only work while they are leveling up. I dunno, was just an idea.
In Silithus.
EPL
Hellfire Peninsula
Zangarmarsh
Terrokar Forest
Wintergrasp Tenacity system
...it simply doesn't work until you force a 1:1 ratio. Which is Tol Barad.
Another timed server-only BG like Tol Barad every other hour wouldn't be a bad idea though, and might cause some of the people who chose the path of least resistance and transferred over to the overpopulated side of their server for Wintergrasp to finally transfer back and even out the realms.