There must be a lot of "little finger" people who are concerned about their limitations if the screen gets larger. I personally owned an android phone with a 4.1" screen and never had any issues reaching over the entire screen using the thumb from the same hand that is holding the phone.
If you've got little sausage fingers and you feel like your going to get embarrassed holding a large 4" phone in public, then don't buy phones that large. Otherwise, stop coming up with retarded excuses for why apple should keep the screen at 3.5".
Ok. Well I am a fairly large man with large hands and my thumb barely reaches the other side of my Galaxy S2. I have to stretch it over and it's not comfortable using with one hand.
Yes this is most likely why Apple chose that screen size. After about a week of fumbling around on that huge screen, and yes you need both hands, to take a picture. Once handed it's not easy. iPhone you can do with ease.
Apple is all about the user experience. They think of every aspect of the experience. No one can compete with their ecosystem. Where is the iTunes equivalent on Android? Doesn't exist. Tight integration with product and services sets them apart.
But most people are fooled on here who want a Android device that bigger specs and a larger screen will make up for it. I did and I thought wrong.
So will most others. They provide these ridiculous screens and 2Ghz processors to make up for their lack of hardware and software integration and services.
You watch, they will make small screens and smaller form factors and focus on software soon. Their strategy isn't working for them. The iPhone 4S is the fastest selling iPhone yet. So screen size certainly hurt them.
Problem with that strategy is that Apple is Software first and for most, and the best at it, by far. Who can compete with them Software wise? Not google, maybe Microsoft. They have a lot of talented people at Microsoft if the red tape did not stand in the engineers way. At Apple they have free reign.