How the heck do you hold your phone? I have to stretch to hit the top of the screen with my thumb. I'm with Apple's HIG that the commonly used controls should be at the bottom.
You can, of course, get your little finger under it move the phone body up so it's easy to swipe with your thumb however that's a lot of hand movement and you need to look at what you are doing.
If you are holding the phone whilst walking you generally hold it as in the image above which is much more secure it would be nice to be able to answer it without having to shuffle the phone with your pinky.
To be honest even moving the thumb horizontally to me doesn't feel like the most natural way to move your thumb. Instead consider moving your thumb from the top left arcing across (i.e. from a 12 o'clock position to almost 3 o'clock) of course you'd need to consider lefties but it feels a lot more natural...
Where did you get that? In my search of Apple's iOS HIG, I came across the exact opposite: Think Top Down [1], where Apple states that important information should be placed at the top "where it is most visible and easy to reach."
Can we try and not make up stuff?
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The location of the slide, I guess, is to allow people to see their lock screen wallpaper. That's my stab at it, but who knows.
