I get the frustration of having to re-farm keys for the dungeons, but without that, is it possible that over time NM will just be people dungeon running?
At least having to re-farm the keys means the NM is constantly occupied.
I was also wondering if the Skittering was the most populated because it was the easiest one to traverse if you didn't have the relic yet. Both the Parch and Sorrow were pains in the rear before getting the relic, whereas the Skittering relic was more a bonus than a necessity.