Pang: Why did the Apple mouse have one button?
Yurchenco: All I know is rumor. And the rumor is that word came down from high that it would have one button because it was simpler. The whole game Apple was playing was simple user interface. If you had two buttons, you had to learn what each one did; with one button, that one button does everything. Apple still works with one button. When I use a PC, I don't have a clue what those other buttons are for!
Sun: The only story I have on that is also anecdotal. Someone else told me that Chris Espinosa said that it would be easier for him to write the documentation if there was only one button, so he wouldn't have to talk about "left button" and "right button." Which is really the same point that Jim is getting at.
Yurchenco: I don't remember strong arguments for two buttons from anybody. I don't think there was much strong support from it at Apple at all. There may have been some software guys who wanted it because they could put more bells and whistled on, but I don't ever remember any screaming arguments there. I don't think it was a big decision in the end.... It's probably one of those osmosis decisions: the consensus is there, and people just say, "Yeah, it's going to be one button."
One little anecdote which I still find amusing. We had this door on the bottom of the mouse, and I needed to mark it in two positions. I decided to have an "O" for open, and "L" for locked. I just made that decision arbitrarily one day at my drafting board. No one ever questioned it: nobody ever asked, "Why did you do that." And ten years later, mice made by completely different companies had Os and Ls on them, and I would be willing to bet that nobody knew what that meant or why that was there. It was one of those legacy things that has roots in no conscious decision other than "I gotta put something down," and it just gets blindly copied forever and ever. I don't see it any more, but I saw it for at least ten years after.