I'm speaking the case of the San Bernardino killers. Using strong alphanumeric pass phrases are anti-usability, the vast majority of people won't use them. Hell, the vast majority of people don't even have strong alphanumeric passwords on desktop services.
So it falls to either 2-factor or biometric to avoid PINs. Biometric of course has it's own problems.
Perhaps people should really carry around a Secure Enclave on a ring or something, and with a button to self-destruct it in case of emergency. (e.g. pinhole reset)
You only need the strong alphanumeric pass phrases on device startup, then you can use TouchID. I bought an iPhone 6 for exactly this reason (employer required strong passphrase, was too annoying to type in on the Android device I had at the time).
So it falls to either 2-factor or biometric to avoid PINs. Biometric of course has it's own problems.
Perhaps people should really carry around a Secure Enclave on a ring or something, and with a button to self-destruct it in case of emergency. (e.g. pinhole reset)