Well, my point was that since 90+% of the computing world uses windows, 90+% know how to use a 2-button mouse. In the US, this basically means everyone, since the computer market is essentially fully saturated. In fact, probably the only place to get a one-button mouse is from Apple. Children are able to figure out how to use a 2-button mouse, unless they are "special." 😉 Otherwise, heaven help them since they won't be able to get a job later in life. And, yes, elderly might have a problem with 2-buttons. But that number is declining every day. In 20 years, probably every senior will have used a 2-button mouse.
Apple should bto it. You can delete the modem, why not the mouse? They already give keyboard options. Why should I pay for something that is worthless to me and will be replaced as soon as I get it? OS X already supports it, why hide it? Apple needs to get over the "not invented here" thing. The one-button mouse should just die like the floppy.