Why can't we use several authentication mechanisms at once? For example I don't think it takes that much more hassle to set-up face unlock, fingerprint recognition and NFC pairing compared to having to set-up
only fingerprint recognition. They are just two simple extra settings, and then NFC pairing and face unlock are pretty much out of the way.
NFC pairing could automatically activate when you try to use fingerprint recognition, being in range. And Face Unlock just activates while you hold your phone in hand, like Google did in Android 5.0.