Well its not that we're trying to ruin American Idol. During the initial auditions, the producers of Idol only let certain people through. Many good people are turned away and many bad singers are kept around to see Simon, Paula, and Randy so that America will be entertained.
Now why do the producers do this? It's simple: American Idol is not about singing at all, it's about making good reality TV and enjoying the cheesy, guilty pleasure of watching bad singing. We agree that a fish out of water is entertaining, and we want to acknowledge this fact by encouraging people to make an even funnier show by helping the amusing antagonists stick around. We just see keeping these contestants around as a golden opportunity to make a funnier show, and to piss off the Producers.