Te Ika a Maui and Te Waipounamu are not names that trip off the tongue for most people. So there is a risk they will be ignored if they become official alternative titles for the North and South Islands. But that is no reason to prevent them following the example set by Aoraki/Mt Cook and Taranaki/Mt Egmont.
In some ways, they present an even more compelling case. The names North Island and South Island may be straightforward and functional but they are also utterly bland, so much so that they are sometimes an object of fun, especially for those keen to paint them as somehow symptomatic of the national character.
It is no defence to say there are many norths and souths around the world distinguishing the likes of the Carolinas and the Dakotas. That simply confirms an apparent lack of imagination.
The two Maori names, or variations of them, appeared on early official maps of New Zealand, including those of Captain Cook, but the practice stopped in the 1950s.