I am almost always infront of the computer, and after having iphone 3g, 3gs, 4, 5, am now having a lumia 730, which at 4.7" is big for me, and I find a bigger screen inconvenient than the amount of time I use the phone. There is a big market out there for people who purchased a phone with larger screen, and want to go back. There just aren't enough models available that are attractive. Plus people want newer models, not older crap. I'm not an apple fan due to its high price (I consider it immoral to sell at this price) and very high repair costs if done officially in India, but for a 4" screen, no good alternatives really.

There is always scope to improve over POSIX, which I admit are pretty bad at many places. However, getting another set of API's right is also a task in itself.