GCN is third in the current gen. Trying to compete with two newer platforms would be very difficult.
With a new system Nintendo can establish a stronger brand, not to mention make an additional bit of money off the people who bought a GCN but will also buy a Wii.
Assuming they don\'t sell at a loss, which they might end up doing to expand marketshare.
GCN didn\'t work, and Nintendo needs a new system to gain a stronger foothold in the marketplace.
You know full well that a fancy controller wouldn\'t have made a splash on GCN or in the marketplace, but the Wii is positioned in such a way that it could conceivably outsell either of the competing consoles.
It\'s just smart business in this case.
And don\'t underestimate the differences between the Cube and Wii. They\'re not the same system. Wii has better hardware, unique control and more internal features.
And it also has way more buzz than Gamecube and has already garnered stronger third party support.