However, the real reason is simple: multitasking. Something the PC of today still has difficulty with.
I'd have to differ on that point. At work (I'm a Linux admin) I routinely have about 20 windows open. 6 xterms shelled into different systems, a spreadsheet or two, e-mail, xmms perhaps, 13 browser tabs, mysql testing, etc..etc.. I reach critical mass before my workstation does, although firefox has a bad habit of barfing.
Same goes for Windows, which I use at home for development.
I find myself with VS.NET (A real monster), iTunes, Firefox, FTP clients, email, and system folders everywhere. Not usually a problem.
I think *games* modularization of the components and good competition are the catalyst for hardware development, whether we need it or not.
I've heard "Do you plan on playing 3d games" asked by many PC salesmen. If the answer is no, then subtract 600 dollars from the system price.