It won't be an MMORPG without the thrill of being camped by someone for 2 hours straight in the open world. Open world PvP will always be the most interesting part of an online game since it has a lot of skill and outplaying. I think a good idea will be to ask players if they wish to have their PvP turned on or off. Since some players don't want the hassle of eventually being camped or killed by an enemy faction player they should be able to choose the option to not be able to PvP in the world. I believe this feature can be pretty balanced and good for a healthy community. The people that do choose to have their PvP on should receive some kind of reward or rewards for it since they take the risk of going out into the world and being killed by other people. This feature can be turned off and on in a capital city for example.
~ Yours Truly
Maybe you can go to a certain NPC or do certain actions to get off your World PvP flag, I really don't like the whole simplicity of doing everything with just a simple click.
The other thing that could be done is making a max level difference, if I'm level 20 and you are 25 we can fight, but if you are level 35 you can't fight me no matter I have world PvP enabled.