I thought of putting the penguins as reason #1, but changed my mind.
Reason #1 is The People. Brilliant, creative, open-minded, strong people. Free and open source software thrives best when there are enough people nearby who can see the value of FOSS. There are many locations with a prevalence of brilliant people, but it is one of those Can't Miss factors.
NZ is one of the world's best secrets. Because people tend to be self-depricating here, no one expects to see such brilliant people here. I suspect that this intellectual divide will deepen as years progress. (You've heard about the earning wage gap? The intellectual gap is an even more fun one to look at, far more complex.)
If you want to see some of the people I'm referring to, look at the people I'm following on Twitter. http://twitter.com/zareasonNZ/following
Note: People often say there is a brain drain in NZ, that bright young university grads move to AU or US or other to earn more money and build their futures.
What goes unsaid is that people who are already bright enough to live anywhere they want -- knowledge workers -- often choose places like Wellington, Auckland, Christchurch, or some place out in the middle of the Most Beautiful Land on Earth.
ZaReason needs community to thrive. Devs and enthusiasts were our original supporters. Now it's far bigger, a wider tent.
The community was, is, and always will be excruciatingly important.
#1 -- The People