Some people were expecting Apple to bring a larger screen in to the next generation iPhone its its event announcing the iPhone 4S. In a “oh yeah” moment Dustin Curtis realised the reason may just be usability, “15 days ago, I have realized another huge downside of larger screens: when holding the phone with one hand, I can’t reach the other side of the screen with my thumb”.
Apple really cares about its products and thoroughly tests them for usability, its one of the reasons they’ve gained such wide adoption – everythings easy to use – even for your mum.
Dustin discuses this on his blog;
Touching the upper right corner of the screen on the Galaxy S II using one hand, with its 4.27-inch screen, while you’re walking down the street looking at Google Maps, is extremely difficult and frustrating. I pulled out my iPhone 4 to do a quick test, and it turns out that when you hold the iPhone in your left hand and articulate your thumb, you can reach almost exactly to the other side of the screen. This means it’s easy to touch any area of the screen while holding the phone in one hand, with your thumb. It is almost impossible to do this on the Galaxy S II.
After reading that we couldn’t resist but do the same, and he’s right! While we cant confirm this is the reason Apple has stayed away from bigger screens, it certainly sounds like them.