I always say the worst thing about an MMO is the players. Also, the best thing. But mostly the worst thing.
I think it's hilarious to have a little bunny world boss. I've always been a Monty Python fan, what can I say. But I wish people would be lighthearted, laugh when things go wrong, make jokes, be fair to everyone, no yelling, no griefing, make it a fun time even if you don't get the rabbit. I wish it was a bunny party! But we all know that's not going to happen. People are going to be angry, annoyed and unfair.
Blizzard could put in particular raid group settings to address at least some of the issues. The raid leader wouldn't have as much power. They can't assign loot. Kicks need to be by vote. These rules could be exclusive to Darkmoon Island, whether the group was initially formed there or not. Or maybe you should have special rules any time a raid is not a guild group (of course guilds will always have their own rules). I don't know enough about raids to know what would be appropriate in other settings, but I have endured a bunny raid.
Of course it's impossible to completely stop griefing, no matter what rules you put in place. But at least no one could steal the bunny. Now if there was just a way to force people to be pleasant..