Why? We could combine forces so Apple employees that come to this forum can see our collective rationale and discussion.
*Merged sammy2066's observations into the first post*
I agree with your observation that the notification bar has to be in black, so that it blends in with the rest of the status bar. Timing pressure shouldn't have been a thing, unless they literally realized how far Samsung and other vendors have come, and despite setting on a lot of money, there are 'cooler' phones out there. Apple realizing they need to leapfrog is great, though it is a bit disappointing to see that they've failed to execute. Mobile operating systems I think still have a long way to go, theres a lot more that can be done to make things more usable, more interesting, and even things Apple could learn from Android ecosystem. Then again, all that is really an aside...
Today we see China Xiaomi making phones that do NOT have a bezel cutout, and it looks great and has InfinityEdge. If Apple wants to deviate using the cutout, they better have some way to showing how that can be better than a "more screen" design. If you look at the mockups of the Xiaomi, it looks like the bezel at the top where the camera might actually look thinner than the bezel cutout at the top of the iPhone X... if that ends up being the case, that would be very sad.