Having the option to guild war would literally help create player driven Open World PvP content.
I agree. Tension between guilds would lead to wars in open world as well. I have seen it on other mmos where two players from different guilds could literally cause war in open world that would lasts hours just by calling their fellow guild mates and friends and them doing the same.
It is a fundamental part of the mmo games , I don't understand why there are no wars here. Is that so hard to implement ?