That matches what they did to touch ID in iOS 10: unlocking no longer actually took you to the home screen, just left you on the lock screen with your phone unlocked for... some... reason. There is a setting to change it, maybe there will be one for this as well.
One of the reasons was that on newer phones (the 6S and the 7) Touch ID was so fast that it was hard to even see the lock screen. If you use the home button to wake up the phone then you would be authenticated and the screen would go away before you had a chance to see anything.
Their solution was to split it into two different steps.
You have the same issue with Face ID. If the "lock screen" went away as soon as you look at your phone you could never actually look at the notifications there.
Clearly they had to do something. Does this work well? I guess we'll find out when the reviews come out.
No, the issue is different. With FaceID, if there was no swipe, your phone would unlock all the time for no reason at all. For example while driving, or while having it flat on your desk and hovering near it, and so on.
I am very skeptical about FaceID. I actually love TouchID, can hardly imagine anything better, but Apple has surprised us before.
Oh yeah, I forgot that I had to change that setting. I definitely hope it's the same with Face ID - I don't use home screen notifications for anything.
Something that "pop" yes. A border flash, a hint at the bottom that means "you can swipe now". The [un]lock icon can stay but it's to high focus to be a good UI.
To be honest, with the full glass, I expected something like.. a full screen fingerprint scanner (have no idea if it's feasible at all). I thing TouchID is the best biometric input for casual operation.