1. Quality Control. If the quality of the fan game is low, people may confuse the fan game with official games and think poorly of the original material. Regardless of the quality of this game, if Nintendo doesn't take down this one, it sets a precedent that the fan games are OK, in which case more will come out, inevitably of low quality.Stupid Nintendo, I don't understand why they won't let everyone make their own Zelda and Mario games it's ridiculous indeed. Bunch of jerks, what could they possibly have to lose from letting the public make their own Nintendo games. Jeez
2. Copyright. The Legend of Zelda belongs to Nintendo. It's theirs, they can do whatever they want with it, and nobody else can without going through them. Enforcing copyright doesn't mean they're mean or anything. The same thing applies to other creators. For example, read Gary Larson's opinion of people posting The Far Side comics online.