Hidden Bosses in Zelda: Twilight Princess

There is a sweet video over at NWiiZone showcasing some hidden boss-type characters in the Legend of Zelda: Twilight Princess. Using the Action Replay, available on the Gamecube, they discovered some way to make these characters appear in the game. I know stuff gets left on the cutting board all the time during development, especially in massive adventures like Zelda, but why couldn't the second boss character be added to the game somewhere, I would have loved to battle that guy.