@Gargron Humans are phenomenally bad at password management and generation - the sweeping majority of passwords are recycled, an obvious personal reference, and not long enough. Hell, I'm a software engineer and most of my passwords are inadequate and I know it but I can't be arsed to make a decent one
A 3D face scanner is harder to spoof than a 4-digit pin, which can be shoulder surfed. A 3D model is harder to make. A photographic face recognizer is useless, however.