Meta is a strange, slightly odd, fickle beast.
It's kind of the internet equivalent of the agora – it's a chaotic place where ideas are brought out, argued over and occasionally there's a bar fight or two.
Critically as the prototype meta, we have folks voting meta-style (to agree or disagree), on topics of discussion (which don't do as well on main sites), announcements (which strictly are not questions and other such curiosities), but we have reputation like any other site...
Critically – It's the one place you can get a enhancement or feature aired out. Sometimes they even get picked up. And, well, sometimes folks are a little too enthusiastic over ideas the rest of the community isn't enthusiastic about. But this is the only way to gauge the sentiment of the community.
As one of the folks who actually got -27. I expected this, and didn't actually care about the reputation hit. I felt a topic that needed discussing kept coming out in comments, and it actually ended up better than I expected. (On the whole, my reputation is positive from that question). And well, more than reputation – meta is the collective memory of the network. You don't always remember just the good things.
And sometimes even the unpopular views need airing and discussion.
In some situations, some announcements are unpopular or controversial and they get downvoted too.
Voting on MSE is based on sentiment. And well, meta is one of the hardest crowds to work with. It's the nature of our audience – folks who are enthusiastic about the network and its workings, and its topic matter.