But, at the moment, there are less viruses on them for precisely that reason. Security through popularity is working for the time being. That and linux/unix/os x have the principal of least privileges working for them too.
No, they don't. We can go through the motions on this "OS X has a better privilege model than Windows" argument, but I know how it'll end: malware doesn't need (or even want) root to win.
