Personally, after being a power PC user for the past 15 years, the 1-button will be refreshingly simple (i am waiting for my next pay-check to order my first Mac).
A fully-keyboard-person, I have never found compelling use for the scroll-wheel even when I had it at work (never bought it at home), and now with a 5-year old at home, seeing her struggle with many an inadvertant right-click makes me irritably wish that MS had offered a single-button

[ Don't start on how I can disable the right-button; it does not work many places; also, most of the PC software is built around the availability of the 2nd button].
My parents have used only PCs since I intro-ed them, and I am looking forward to exposing them to the simplicity of the Mac, beginning with the mouse. Once Apple starts offering the 2nd button there will be software that cannot be fully exploited with a single button, and there goes your 'simple'!
My circle (of family and friends ) is 100% PC, but other than those with jobs in IT, very few use the right button : the menu is where they go every time. I have even seen that some get flustered when the right-button clicks by mistake
I can empathize with the frustration of a power-user who is heavily dependent on a particular style of working, like the more complex mouse, but I do not believe power-users are in any way 'the majority'.
Just because the vocal majority in these forums wants more buttons does not make it a universal demand, more likely an 'elite' one. So I am not surprised Apple is ignoring this.