New Zealand has a constitution ...
True but not a 'written constitution' as they are generally understood.
We have what is known as a 'constitutional framework', a system by which the government is run. It is made up of The Treaty, the Letters Patent, Orders In Council, the Cabinet Office Manual and other things such as the Bill of Rights.
What most written constitutions have is something that says the government can't change anything in the constitution without more than a simple majority, much of the US constitution can't be changes without a 2/3rds majority. Any NZ law can be changed with simple majority, such as the Bill of Rights.
On the upside, governments can't say "It isn't against the constitution" and isn't bound by laws made for other circumstances.
In the context of this debate the lack of a written constitution could allow us to have a meaningful dialogue about Maori claims, such as 4G, and the place that Maori should have in NZ without that place being stuck in whatever time the conversation is had. It can evolve and change as the country evolves and changes.
Sure we need to get over our differences but saying: "Right from today everything is different" just doesn't work. People get over stuff when they do. But, as usual, 'they' are not the only people who need to get over stuff. 'We' need to stop saying things like "If the Maoris can claim XYZ, why can't I?". Have any of these 'crazy claims' gone anywhere? No, they have not. As my mother might have asked "If the Maoris jumped off the roof, would you be getting the ladder out to go next?".
We all need to grow up and at least attempt the reasoned conversation that would move this country forward for everybody.