OK, OK, you win Swordmaker. Apple was trying to appeal to street people all these years and somehow I missed it. Honestly. I love my Mac, but I only took a sip of the Kool-Aid. If a single-button mouse was such a great idea, why introduce a mulit-button mouse now? (He asked respectfully.)
In a way you are right... they were trying to appeal to people who wanted to use their computers as an appliance... to use it as simply as possible. I have met numerous PC users who STILL, after years of trying to use the PCs as appliances, have problems remember whether a specific action requires a left or right click. I have never run into a Mac user with the same dis-clickia problem. ;^)>
The point, respectfully submitted, is that more than one button adds levels of complexity. "Do I left click? or do I right click? What happens if I click wrong?" Numerous studies of user interface have demonstrated that for most users a single button mouse is easier to master and use. Apple took these studies to heart. This finding was demonstrated to me quite impressively in my experiences training the neophytes on both platforms simultaneously and differences in the learning curves between one and two button mouses.
At the time I started doing this training, I was an Amiga user... with a five button, trackball device. I had moved to there from the original two button Amiga mouse. Incidentally, I developed the database (which is still in use 18 years later) on my Amiga emulating a Mac and tested the PC version on my Amiga emulating a PC!
As a user gains confidence and mastery of the one button mouse he may find that it is more convenient to move to a multi-button mouse or other input device. Would you hand your grandmother (or your mother) a sophisticated gamer's input device as her first experience with the mouse/pointer metaphore?
As to why Apple is introducing a multi-button mouse now, note that their computer still ship with the one button mouse... the Mighty-Mouse is an after-market offering for those who choose to upgrade.
Me... I'll stick to my Logitech 3 button, scroll wheeled, thumb trackball. . . which I started using with a Mac 6400 in 1995 (I think) in an ADB version... now in a USB version that works with my G5. As I said, we Mac users CAN get along with a single button mouse . . . in fact, you can do everything normally done with it. . . but if we want more, we go and buy it.