Because that's where you are when the data is analyzed. That's how smart it is. It sees you delete game data of a game, so it makes sense you might want to delete the game app as well. So the option to do so is offered. The same as when you're asked if you want to keep game center info when you delete a game. I don't use game center much for anything. I have game stats and achievements there, but don't spend much time there. I've never deleted game data in the game center before. I have some there I wish I could add to the App. LOL l lost a lot of progress and achievements when I upgraded to my iPhone 5 2? years ago. Oh well.