Ah, the always easy to discover (only in the mind of the designer) gestures.
Let's not forget that with the current gigantic size of phones, I can actually easily reach less than 50% of the screen. The top part is completely out of reach.
Because I tend to hold it with my left hand and tap with my right, I've deliberately moved icons around until my most commonly launched apps are as close to the bottom right corner as possible.
I've actually stopped using the 'switch between running apps' UI almost entirely now because with that done, it's faster for me to tap to the home screen then on the icon of the app I want to switch to.
Let's not forget that with the current gigantic size of phones, I can actually easily reach less than 50% of the screen. The top part is completely out of reach.