You have to remember that Nintendo was a graphical powerful company. The only reason why Nintendo doesn't have a Wii with powerful specs. is because they didn't want to, not because they can't.
And you have to remember that Sony was not always a graphical powerful company. Both the N64 and Gamecube were a lot better in terms of hardware specs. and graphics than the PS1 and PS2.
This is the first generation that Nintendo makes an underpowered machine.








