The "respectable" explanation is that too many voters are feeling left behind or excluded from the wealth generated by free trade, foreign investment, multi-national business and globalisation in general. But that is not a subject anybody would be afraid to express.
In fact newspapers contain plenty of comment from opponents of free trade, foreign investment and "neoliberal" economics. So it is hard to believe that has caused all this spluttering frustration.
The less respectable explanation for the mood is resentment of multi-racial (read non-European) immigration. That is the subject that dares not speak its name. The underlying cause of all the anger and frustration must be that modern gagging order known as political correctness.
Sometime between now and the September election Winston Peters is going to blow off the gag. He is probably weighing up right now the best time to do it.
As Don Brash demonstrated with Maori "separatism", once people have blown off their steam on these subjects, the issue quickly dies. I'm guessing Peters will wait until May-June but I'm hoping he blows sooner.
Personally, I've never been more well-disposed to multi-racial immigration than I am right now.
I spent much of last weekend with my father who is now in a rest home nearing the end of his life. All the staff there appear to be from somewhere in Asia. They are doing everything for him without a qualm or complaint.
This is one of the jobs that, according to the most respectable criticism of our current levels of immigration, are being denied to New Zealand's 70,000 young "Neets" (Not in employment, education or training.)
The job deserves much more than minimum wage but I doubt it is just the pay that keeps our Neets from this sort of work.
As in hospitality, farming and other industries with labour shortages, we need migrants. We need cultural variety, we need more people.
It is magnificent that New Zealand's population is growing so strongly now, after being static since the early 1970s, and I'm looking forward to the debate with Peters.
But I also understand the frustration with the media. I felt it too during the event that was probably seminal for the electoral convulsions in the UK and the US last year.
Trump believes Brexit would not have happened had it not been for German Chancellor Angela Merkel's "catastrophic" announcement the previous year that asylum seekers could come to Germany for their applications to be considered.
The world watched the consequences on television - a human tide of migrants walking into Europe, Balkan states trying to stop them at the gates.
But to watch those scenes on television was to see a strange disconnect between the reportage and visible reality.
Editors decided this was a story of desperate people in mortal danger deserving only our compassion. Cameras focused on women with children on the road to go with the soundtrack but viewers could plainly see the migrants were overwhelmingly young men seizing an opening to a better life.
Uncontrolled immigration on this scale was not a refugee programme, it was an invasion.
"Catastrophic" was the word for the coverage too. When the media is politically correct it needs to be correct.
We have become uncritically reliant on academic research that does not use the same language. It supplies appalling figures on subjects such as domestic violence, child poverty, homelessness and obesity, and leaves us unaware of how widely these terms have been defined.
It asks the public to accept facts and figures that don't seem right somehow. The cumulative effect is frustration and distrust, and we need to fix it.
