“Show previews always” can be set up

I am very aware of that, and that's something I specifically do not want unless I unlock my phone.

What about when your finger is wet or you’re wearing hand gloves?

Touch screens with gloves is a pain anyway, even with those "touch ready"-ones. And how many times do you wear gloves? I get annoyed by faceID almost daily, I don't wear gloves daily. Is touch-id perfect? Absolutely not, but did I prefer the user experience? Without a doubt.

That said, I like the screen real-estate we gained, but as android phones have shown, in-screen fingerprint sensors are possible. I don't know how secure they are though, and with the One+7T I have here, not having tactile indication of where it is, takes some getting used to.