is that the reason or just a convenient side effect? the last two models had to move the lenses around slightly so they could capture whatever they called their stereo AR/VR type acquisition so the pupil distances worked correctly. after that, there's only so many ways to arrange 2 or 3 lenses.
Because when you pick it up, your hand is covering up the middle of the phone. However the top quarter is unobstructed.
> And why do the cameras keep moving around?
Easy way to tell models apart.