She's big on ideology, a fan of discussion and consultation, she's empathetic. Perfect UN material.
Who needs the stress and day-to-day tumult of being Prime Minister if you don't have to?
Here, she is trapped in a finite political cycle. Her time will come and go. And she's at the top of the tree already.
At her age (38) if you want longevity and you've got political aspirations and a 'change the world' mindset, you need to go further afield. Think about it, she didn't expect to be Prime Minister so soon, let alone even leader of her party.
It all happened fast, and she's already half-way through her term.
In that time she's managed to navigate a new coalition government, a baby, a national crisis, and working the international stage.
And as far as the international press are concerned, she hasn't put a foot wrong. If you're an ambitious person, you're already thinking of the next step.
Why would you hang around if you're already able to tick the Prime Minister box?
When Ardern famously appeared at the UN with baby Neve watching on, it made worldwide headlines. Not because of the impact of her speech, which was largely to an empty chamber, but because of what she represented.
At the time, political editors were hailing her as "the torch carrier for progressive politics." The BBC's Nick Bryant called her UN performance "the most interesting debutante of the year".
So how do you capitalise on all that exposure and all that international goodwill?
You strike while the iron's hot.