The Dim Post has a great analysis of the reasons behind Labour's election rout. Harsh, but fair, as the Aussies might say. It's quite short so be sure to read it. To quote a few lines:
Congratulations to the Green Party for their improved result, and special congratulations to Sue Bradford; her bill closing the Section 59 loophole in the crimes act was the other key ingredient in making the evening what it was. Your hard work in pushing through trophy legislation in the face of overwhelming public opposition has helped put Judith Collins (or some facsimile thereof) in charge of the New Zealand welfare system. I hope you think it was worth it.
And congratulations to all those who promoted and supported the Electoral Finance Act; I trust you are thrilled with the outcome of the election and that you will enjoy the process of watching the National Party write their own electoral laws in the same spirit of spiteful hyper-partisan vengeance with which Labour passed the EFA. I’m sure new ACT MP John Boscowan will be delighted to help them out and that he’ll also take a very keen interest in gutting the MMP electoral system while he’s at it.
The only march I have ever gone on in my life. Who would have thought Mr Boscowan would end up in parliament over that?
I suppose a general point is that when you think you are the natural party of government, and cannot lose, there are no restraints on the silly legislation you will pass. Some might call this dangerous extremism, but for others it is fact the natural centering effect of democracy, when they get tossed out.