I'm originally from Europe.I know things are a little different in Europe, where perhaps the biggest social issue is immigration. Dunno about you Kiwis though
However, in New Zealand. The biggest social issues are alcohol, drugs, crime and the maori issue. The new government have increased drinking age, increased the number of police and implemented a three stikes out policy. New Zealand gets a lot of immigrants, but it's not an issue because they have to be qualified.
However, the economy is the biggest issue. How to deal with the emigration to Australia, enviroment, firing regulations, minimum wage and how to inprove economic performance. New Zealand is not as rich as Australia, because it is too small for economics of scale. No one realize the last part though,