- Many of the big "UX" benefits would not be possible without massive changes to entrenched business processes. e.g. Visual voicemail was something that AT&T needed to support. Likewise, unbundling all the "Crapware" is another area where Apple forced the carriers to change their business processes.
Apple had the ability to do this because of their momentum. In 2007, Apple had revolutionized the music industry, was on its way with TV and movies, and clearly someone at AT&T wanted some of that momentum or certainly didn't want Verizon to have it.
If anything, the launch of the first iPhone showed UX alone wasn't enough to dominate the market. The G1 iPhone sold well, but not to the scale it is now. Only after the price got chopped did people move to it en masse. Apple was able to do this by having the world's best operations team and forcing extra-subsidies from the carriers.
Now the UI did get people excited and you can't separate the success of Apple from the strength of their UI, but this article would make you think that the great UX was the primary reason Apple has succeeded.
Design is important, but Dribbble is full of beautiful app designs that sell 10 units a week, where as you will find many horribly designed, modern sites, that are dominating new markets.