Or maybe it's just people like me and you that are simply not informed about what people really care about.
Myself, I would love to see quad core in an iMac (or heck, a laptop, for that matter), but that's only because I'm a computer geek that thumps his chest about such things. Not that I wouldn't use them if I had them (you can never apply a photoshop filter fast enough), but if the other cores are not there and the operation takes a few seconds or even minutes longer, it doesn't affect my quality of life.
Most students, their parents, or casual users don't notice either. The people who do notice are the people buying XServes or Mac Pros. They notice and care. Another set of people that notice are gamers who would like to put Lamborgini engines in Yugo bodies - and a superfast headless mac with lots of expandability would be perfect for them.
But Apple decided a long time ago that that is simply not a market that they care about. Years ago in fact. We can continue to mourn that fact or we can simply move on. For me, I just got old and no longer have the need for such a machine (my game playing days ended long ago). If you aren't there yet, you can generally get kit like that sub $800 running windows, and you should. Apple has decided that is not a market they care about, and will do very little to court your business.