If we had another 1 mill pop we could afford a light rail system.
Think about this Celia...
...and a football ground. How have we missed this?
Auckland may be getting a light rail system, and we've got about 4 football grounds, all of which suck.
But the most important issue is that Wellington doesn't have a big enough international airport, so the immigrants don't move there unless they're really motivated to. The other one is - where would they all live? It would be all very well to have J82's Hong Kong apartment blocks for a million+ population, but we can't even get those in Auckland because of all the NIMBYs, and it'll be worse in Wellington where the NIMBYs can stop even harmless sports grounds.