Need to input an additional passcode which is unnecessary when using a cash card, and still need to input the PIN. It is remembering 1 more thing in exchange of carrying the card.

Not as insecure as I first thought as just scanning your face and getting authenticated, nor as convenient as that would be.

I don’t see it getting so popular that it replaces cash cards. There is not a huge advantage to the user so banks probably cannot convince that many people to give up their biometric data for this service.