I am embarrassed for many people posting here to be honest. I've been here for a long time and I swear every year the Chicken Little types both here on this forum and in the world at large are becoming a larger percentage of the population.
There are legitimate concerns with privacy regarding any device that carries our personal information. No one disagrees with that. Biometric unlocking, pattern unlocking, and so on are designed to help us have some security while also having some convenience. IF you're truly concerned about these things, put in a long passcode and use ONLY that passcode. Skip the biometric identifications or pattern unlockings altogether.
It is legal in the US and perhaps some other countries for you to be compelled to unlock a phone with Touch ID or similar, and likely will be just the same with Face ID and similar facial and retinal scanners. This is not new. The key is that Apple's seems to work better. Just a few weeks ago reviews of the Note 8 made comments about the facial and retinal scans as being gimmicks and just for publicity. So it seems they're not that much better than they were a few years ago on some devices. Maybe this will be different.
Ridiculous comments about it being useable while sleeping, or while being robbed, or whatever are honestly irrelevant. If someone wants you to use a finger, that's no more secure when you're under duress. If anything, this is better because the phone is designed to allow other bypass methods (the two button press) that will lock it for a PIN.
I'm not even of the camp that "if you have nothing to hide, you have nothing to fear" people. Security is an issue and is real. But this isn't making it easier. Just disable it and ALL biometric, pattern, and short PIN numbers. Use longer PINs and guard your phone. Put nothing on it you don't want others to see. Have some common sense. Stop with the fear mongering.