ID cards, biometrics, and massive, centralised databases - putting aside civil liberties for a moment, what about the questions:
How do they fail? How often will they fail? How will people respond when they fail?
Because they will. There is probably not one technology that hasn't, and there is no reason to think these are different They will fail due to hacking, carelessness (lost devices, poor password control, use of insecure machines), software errors, computer failures, fraud, forgery...the list goes on, resulting in lost, deleted, corrupt and stolen data. Pretty much any biometric measure or an ID card can be forged very quickly, and they are generally supposed to last 10 years. Finger print scanners have been bypassed with gelatine casts, iris and face scanners with photos.
Even worse, once these are introduced, security people become dependent on them/'complacent', so when they fail, they fail badly, making the whole system even less secure than it was before.