I don't think the consumers would be all too impressed if MS and Sony started to outright copy everything Ninty does, they are also targeting very different demographics. What works for Ninty may turn into shit for MS/Sony, and just trailing after the current market leader like a driveling dog would make the two monoliths look weak and washed up.
Also, I don't think neither MS nor Sony really have much faith in the Wii's long lasting appeal and value as they have made pretty clear on many occassions.
I know Harrison spoke well of the Wii, but then again, he's no longer with Sony and needs some allies to help him save Atari from the "red dragon" (bad numbers).














