Passports are one of those critical documents you never want to lose or have stolen from you, especially if you're in the midst of a vacation in a foreign country. Getting a temporary passport is a lengthy process that will probably require you to prove your identity to your country's embassy, so why not take a few preventive measures that may just make your life that much easier if things go south.
After all, life is unpredictable, and you never know what kind of weird situations you may get into and what kind of crucial documents you may end up losing.