Personally, I am under the impression that the Wolves' Den had been designed, most of all, to be a testing ground for any future - and meaningful - PvP content.
Sure it was presented as "content", but as many of you pointed out it was pretty dull from the very beginning.
I don't know if it was ever meant to "succeed" or just serve to test gameplay, and also for all kind of code/server/behavior stuff.
Frontline sure looks like their first true attempt at some valid PvP content. Unless I'm totally wrong - not a real PvP pro here.