This recent article has outlined some of the arguments against having a more liveable city. It concentrates on features of American cities, but I think most of the points apply just as well to NZ cities.
Of course, Auckland already does very well on the liveability stakes, recently being ranked number 10 in the world by the 2014 Economist Intelligence Unit’s Global Liveability Index. However, the big stumbling block for Auckland on rising in those rankings is its transport issues, especially around public transport and cycling.
There is no doubt that if Auckland had a 10% cycling mode share and a 30% public transport mode share, it would hugely increase the quality of life if its residents.