That said, I find Face ID extraordinarily troubling, because it normalizes the idea that your phone actively scans your facial features during use. Just like carrying around an always-on pocket beacon became part of the 'new normal' with the introduction of the smartphone, a phone that looks back at you during use will become part of the new normal, too.
When you combine this with business models that rely not just on advertising, but on promises to investors around novelty in advertising, and machine learning that has proven extremely effective at provoking user engagement, what you end up with is a mobile sensor that can read second-by-second facial expressions and adjust what is being shown in real time with great sophistication. All that's required is for a company to close the loop between facial sensor and server.
Apple is unlikely to be this company. But Google, Facebook and Amazon are. What I anticipate is the next generation of Home and Echo to have cameras (Amazon is already moving in this direction), along with whatever piece of hardware Facebook produces. The idea of devices that look back at you will gain acceptance, just like always-listening voice assistants have gained acceptance. All of these will become input sources to learning algorithms.
What is already an incredibly potent toolchain for political manipulation will become even more powerful, with no oversight, accountability, or even much understanding by those who built it on the way it can be profitably used and misused. Its effects will be field-tested in democratic elections that affect the lives of billions.
This is what Zeynep Tufekci has called the architecture for networked fascism, and by manufacturing a mass-market device with active facial scanning, with the best of intentions, Apple has moved us a big step further along this dismal road.
So Facebook will add its own spin on animoji, requiring full face-tracking permissions - and then begin quietly mapping emotional response to every timeline entry.
The tech is out of bag and apple not doing it would just delay it by a few years. Managing a world where microphones and worse are everywhere and are being used by autocracy is how we should be acting going forward. Accepting that this is the world and dealing with the changes should be the focus, not trying to prevent tech that will be created whether or not some people like it.
edit: I do agree with your tweet about how it changes social norms although.
We've been able to bug houses for years, but only recently did Google and Amazon normalize it by selling an always-on network-connected microphone (and now camera) as a consumer product.
Apple built it with secure enclave, so they are actively protecting your privacy.