They got a bit tired of killing people on the bridge outside Lumbertown.

In a rather amusing forum post, a CM confirms that TERA Online's developers have Battlegrounds planned.

The feature, the devs say, is in response to how frequent players in PVP servers are going around looking for fights, such as sitting outside of one of the more high-population towns and attacking the people who left. The presence of guild warfare will still be present, of course. 

This comes with the unfortunate news that it won't be ready for the live servers, but in the words of the post, "this added time means a more polished feature and overall experience."