Google needs to solve that part of the problem. Apple has already solved it with TouchID.
Google needs to do the same and mandate all OEMs must certify for fingerprint scanning technology (that has a high-standard of accuracy and security, not the gimmicks HTC and Samsung have tried before), or at least incorporate the same kind of technology Nymi uses in all Android Wear watches, so you can unlock the phones with that. Google should either acquire or replicate what these guys are doing:
I think the idea is that the password (which can be made complex if you don't have to enter it that often) is analogous to the "passphrase for the key", while Touch ID serves as the normal "passcode to unlock the device".
Google needs to do the same and mandate all OEMs must certify for fingerprint scanning technology (that has a high-standard of accuracy and security, not the gimmicks HTC and Samsung have tried before), or at least incorporate the same kind of technology Nymi uses in all Android Wear watches, so you can unlock the phones with that. Google should either acquire or replicate what these guys are doing:
http://www.getnymi.com/