The ability to engage in World PvP has existed since the day of the launch. People who enjoyed World PVP have been engaging in it since the beginning.
What happened was is that Phase 2 introduced the Honor system, which allowed people to EARN GEAR from pvp activity. Suddenly, everyone who really didn’t care for pvp but like gear showed up to play. Gaining honor is why these same people obsess about DHKs.
When Battlegrounds are released, the fastest way to get gear will be in Battlegrounds. That will leave the world pvp back in the hands of people who like pvp for the sake of pvp, just as it was in Phase 1.