Why have they not done this?
Biometrics: Check
PINs: Check
Biometric + PIN: WRU??
For those who wish to be more secure, a combination of both would be a great option.
Neither one is absolute. (Phone Biometrics are laughable at best) Having the option to use a PIN, Biometric, or both, seems to be a decent "halfway" point until the biometric technology improves. Even afterwards, it provides an additional layer of security for those who may want it.
This combines two factors of authentication: "Who you are" and "What you know."
It maintains Biometrics for those who want the ease of access.
It maintains PINs for those who don't feel Biometrics are secure enough.
It would then allow the combination of both, if you want to be even more secure. Not only two factors of authentication, but one unique to you (biometrics) and one which can be changed when desired (PIN).
Yeah, the current generation of "mass public" readers are woefully insecure. It is better than nothing (unless you are under the impression that you are completely safe using it). Allowing the combination of both (AT THE SAME TIME), provides the security of both. As biometrics become more reliable, you can still have that added security layer of the PIN.
I don't know.... I just don't understand why this isn't an option (at least it is not with iOS 8.x)