Well if this were done there would need to be a bonus for going into the pvp instance to quest.
Maybe 25% bonus xp on quests in the pvp instance? Also a chance of players dropping campaign badges or something might be nice. I'm sure there are better ideas but you get what I mean.
As long as they give better rewards in the pvp instance I'm sure more would take the chance.
Or maybe if you load into the pvp instance you get flagged for 24 hours and can only go into pvp instances until the timer is up. That way you can't just tuck tail and run as soon as fighting starts to happen.