> I was also a bit annoyed at having to renew my New Zealand passport before I left (my old one would have expired halfway through my stay here), because my old one had cool stamps and visas stuck in it like Japan, Samoa, and Vanuatu.

You don't get to keep the old passport? Or do you mean you'd rather have all the stamps in one place?

U.S. Passports are legal to use as identification even after they've expired; when we get renewed passports, we keep the old ones. It never occurred to me to wonder if other countries might do it differently.