Reach Navigation is great, but the top isn’t all that unreachable
Completely agree with the fact that with increased screen sizes, the top of the screen has become a little harder to reach. However, the touch zones that are represented in the post, might be making a slightly incorrect assumption.
From what I’ve observed, with the increased size, people don’t really hold the phone the same way they’d hold a 4s. The grip would tend to shift a little upwards, so as to balance the increased weight and size. With a different grip, the touch zone will look a little different.
Hurff’s touch zones came out in 2014 just before the release of iPhone 6 and is based on the assumption that the thumb is anchored to the bottom right corner. That sort of grip, isn’t ideal for the iPhone 6 or 6Plus, as it’d disturb the balance of the phone if the thumb were to try and reach at the top. Instead, people grip their larger phones differently, which tends to shift their thumb anchor a little upwards and more towards the centre than the bottom of the screen. Touch Zones look different if the position of hand is taken into account as well.
If I were to pick the touch zone on the right, the changes made to the UI in iOS 11 would make some more sense. (The top navigational bar containing bold title, but then offering the search bar or some other interact-able element exactly below the title, instead of bottom of the screen).While it makes sense to shift some of the elements of the navigation bar downwards, shifting the entire navigational structure to the bottom would potentially leave some interact-able area at the top
However, all this is just conjecture at the moment, as I don’t have enough data to conclude if either one of the touch zones accurately represent the reach of the thumb but in my opinion it’s worth noting that the phones are held a little differently every time the screen size change.