I did participate and tried to look for people to do this. But for the solely reason of getting charm points from the creature that spawns there. I was probably one of the few players that did this on Kenora.
Here is what I have done: Since I was doing bestiary of some really weak mobs that were dropping these berries, I payed attention and hoarded 100 of these berries (the Rapid Respawn would be perfect to get those winterberries if people had some reason to join it). After that, I've divided these 100 winterberries to 10 different chars. With these characters I went to the cellar of the world change one by one and used the winterberries, then I log out and log in the next char of my account list that had 10 winterberries and repeated the process (you can only use 10 of these berries per character, which is really bad). When I reached the mark saying that there was enough winterberries over there, I went back to my main char and did a few actions over there, like stomping the winterberries at the center or just waiting until the monsters appeared. I killed 5 of them and left the whole place, since I would never bothering doing whole thing alone.
Frankly, that's a pretty weak world event that needs some sort of new reward or a completely rework, probably not that bad regarding lore when compared to the one where you need to do tons of chores in order to make baby demons happy (?????) but it is very boring and unpleasant in my opinion. Many casuals do not have time or patience for something like this, and a guild would be better spending their time on other things like going after profitable bosses.
Curious enough, it is one of the few world events where Free Accounts can fully participate, so if they can somehow allow to exist a decent possibility of individual reward (maybe similar to Santa Klaus presents?), I think that this world event can be potentially an excellent one in the future.