Im astounded by the comments blaming the users and not bad design by Apple, so lets get things straight:
1.- FaceID does not work all the time and sometimes you need to enter passcode while maybe distracted.
2.- Even with a long passcode, they are recording it so they can reproduce it easily.
3.- Someone with a passcode to a device should NOT be able to remove the security keys and change the password of the icloud account. Apple should ask master password or biometrics without passcode for certain changes.
4.- It is a passcode for the DEVICE and NOT for the entire appleiD account.
The recent adition of security keys to increase the security of appleID and that they can be removed with just access to a device is a complete joke in security design.