We (the people of New Zealand) generally don't want to change the flag because we've no good reason to..
The current government (and mainly that government's Prime Minister, Key) want to leave a lasting legacy that isn't the series of fuckups that keep coming to light and/or pushing bad/unwanted legislation (eg off the top of my head, the new Health and Safety legislation that doesn't improve Health or Safety in dangerous industries), so they started a flag change at a predicted cost of NZ$25 Million.
Generally the public barely gives a fuck, which makes the whole thing even more stupid, particularly as the money spent has already reached the predicted total cost and we've not even started replacing the flag yet.
There is no doubt politicizing of the issue from Key's part but I don't think the notion that "no one" wants the flag changed is true. It's been been brought up in the past but never gained traction. The opinion polls seem to show that the idea does have a sizable group of supporters.