I think the idea was to prevent the attacker from being able to replace the screen without the owner noticing. Replacing the screen may allow the attacker to pl

I think the idea was to prevent the attacker from being able to replace the screen without the owner noticing. Replacing the screen may allow the attacker to place own custom hw in the device without the owner noticing (screen is large, has good exposure to audio and video, etc.). For the FaceID to be secure - which I believe it is, within reason - the chip needs to be able to establish trust with the other components of the chain. It's not achieved with thin solder and glue, but with cryptography. I don't think what gluing it to the screen achieves in terms of security, it's not like you can replace the faceid sensor with a different one anyway.