I've had this discussion in several other forums, but it boils down to a decision by the majority: at what point does ease-of-use supersede function?
Bigger desktop cases offer more space for more stuff to fit into, and portables remove that advanced processing muscle in favor of great portability. At their extremes, a desktop will exponentially outperform a tablet, while a tablet can be used anywhere, anytime. It's clear that your average Joe, who is really the driving force in the market, doesn't have much use for the power offered by desktops anymore.
I think those of us who grew up with desktops hold their unique benefits more dearly than those who use computers for more general stuff.
It always sucks having insight and perspective on products and their uses only to see the neophytes pass on those benefits in favor of their own preferential satisfaction, but that's the story of, well, just about any product throughout history.
