Fill in the blank for millions of users out there, and you start to get the picture of why Apple has not done the xMac. Until the industry can offer other solutions that eliminate the "if not for the...." dilemma, from a business/profit/share value, Apple's behavior is very obviously in their own best interest right now.
How is it in their best interest when I haven't bought another Mac in 8 years? I would be about my second replacement by now.