A rather good point about the use and meaning of flags. The Union Jack on the New Zealand flag represents the injustices in our history.
The very basis of the argument for keeping the flag is historical. The world wars are usually used to justify retaining the standard our soldiers fought and died under. But we aren’t that country anymore. Our foreign policy is separate, and our institutions are independent from the UK.
Our system of government is evolving down a different track. It is more thoroughly democratic, more efficient, and more open than the British government. The wrongs done to Māori are slowly being addressed. We are moving on from the darkness of colonization. Shouldn’t our national symbol move too?
The other argument against change is about cost. This is a non-argument. It is the outright refusal to engage with the issue. It avoids the question, and thus the responsibility. The government spends a lot of money on things which are not strictly necessary. Changing the flag isn’t one of them.