Also... Prices!
Mario Kart still selling for $36 in Costco. Say what? I normally stick to the under $5 / under $10 sections on Steam which includes a lot of big name games. I have over 130 of them. So the Wii has Sports and not much else in my house.
Yes, fun > HD graphics but you'd have to give me a pretty good demonstration of extremely amazing fun *before* I parted with $36 for a game, on an ageing console. Age isn't a factor per se, but analogue ports on TV's and computer screens are fast disappearing.
Perhaps I'm not the target demographic, but its a pretty dangerous game for a console maker to ignore other form factors as competition. I can't see the tablet generation paying $36 for a game either.