I never understood why criminals steal people's passports. How could they possibly use them? It's somebody else's picture on the passport.
At least on my passport, the picture could be CAREFULLY cut out, replaced, and re-embossed. I have no doubt the alteration could be detected, but it's a question of how easily, by whom, and in what part of the world.
Furthermore, in many countries there is a trade in "black passports", that generates income not when they are successfully used, but when they are successfully sold to the unwitting sucker who buys them.
In a different part of the world, supposedly every year a few vacationing Australians and New Zealanders go missing--permanently--their passports and identities stolen for black op's operations.