I've read about a few conservation programs where zoos had a central role in aiding with the resources and the reproduction and building of numbers of animals to reintroduce in the wild.

But besides that, it has been close to a decade I've been to a zoo and I don't miss it.

At a point in my life I wanted to get a degree in biology to work at a zoo. Nowadays, I think the best "zoo" is 500 square kilometres of land, with the closest human settlement 50km away.