One handed use on these big phones seems to come down to two methods:
1. Bracing the sides to keep the phone upright.
2. Balance the phone on four fingers on a shallow angle, while reaching your thumb across the screen.
Is your one hand usage on a 4.3" screen anything like this?
http://www.youtube.com/watch?v=ZTMHqLsZmI0
If so, holding the phone almost flat in your hand (looks about 20 degrees), while balancing on four fingers and hunched over is not what people are looking for when they try to use their device with one hand. I think that's why some are confused, it's not that you can't use it with one hand, it's that it's not comfortable, or even feasible depending on what you're doing.
With my iPhone I can support the bottom with my pinky and hold the phone with one hand at any angle. In number 1 above, you can't reach the whole screen, since you're fingers are applying pressure to keep the phone upright at that angle (gravity). In number 2 above, the thumb reach is greater, but you seem to be limited in the angles you can hold the phone. It seems the sweet spot is between 0 degrees (laying flat) and 45 degrees before gravity slips the phone out of your hands.
If I'm sitting back in my chair, or on the couch, or even walking, I hold the phone more upright. You can't play the "Balance the phone on 4 fingers" game in these situations, requiring the use of two hands.
