Those doors are most likely a place-holder for a Gelmorran instance at some point in the future (If they ever decide to make one, it's useful to have the architecture already there. I speculated on this back in the spring, will have to find the thread). Remember that the current marker used on maps can and usually is re-adjusted once an instance is added. For example, pre-2.5 the Keeper of the Lake map marker is near the fallen Agrius, but in 2.5 it's moved to where the instance "entrance" is instead. My assumption that, when the Gelmorran Ruins becomes its own dungeon (if ever), the marker will be adjusted as such.