Does anybody know why the Wii and Gamecube versions of TP are mirrored?

Because Link has always used his sword with his left hand and for the Wii version this needed to be changed in order to make the game comfortable for most people (who would rather hold a sword in their right hand as opposed to their left) so nintendo decided to mirror the game to go with the change of hands. So in the Gamecue version link holds his sword in his left hand and in the Wii version link holds his sword in his right hand.