biometrics have many advantages, but introduce all sorts of new issues; eg,

with a traditional key, I can lend it to a friend or relative if I want to let them into my house. You can't do that with a fingerprint.

I have actually seen instructions for a USB fingerprint device that advises to "register" at least one finger on each hand - so that you don't lose all you data if you should have the misfortune to lose a finger or a hand...