With the original event, I was a healer for my guild and we organized around it, often defending the Crossroads. It was fun at first, but then it really got old as a single griefer could offset a few people trying to keep the place open. Cities filled with ghouls was funny at first, but then one realized that we had things to auction, skills to buy and then it started to get old, really fast.
Comparing this with the heyday of city raids to kill leaders. This was fun as it could happen any time but required the attackers to be organized and in larger numbers. I liked this very much, especially as a impromptu raid healer. Compared to the zombie event that could be perpetuated by a single jerk no thanks. Just make it opt in event so people can fight zombies and each other.