I've come to the conclusion that there's no point in trying to convince people this is a good addition to the park. There are enough American Idol fans that should keep this attraction popular for a while. Personally I think the key is always having a cast member plant in the show that the judges can make fun of.
I enjoy watching the early stages of American Idol, and I know I'm not alone in that. I have a passing interest in the show once they get to the Hollywood Week and beyond. With that said, there are things in every park that I don't have much interest in, for the most part they are shows, so I can't really fault people for not expressing interest in this one.
In the Magic Kingdom I don't have much interest in Tom Sawyer's Island, the Riverboat, the TeaCups, or any of the Dumbo style rides. In Epcot I have no interest in the China and France shows. In Hollywood Studios I'm not a fan of the Beauty and the Beast show or the new Animation Tour, and I have no interest in seeing the Playhouse Disney show or the Narnia walk through. I'm also not devastated about Fantasmic being cut down to one show a week. As for the Animal Kingdom, I think the Finding Nemo show is overrated (like Fantasmic), but I think that's predicated more on my lack of attachment to the music. I also wasn't a fan of the Tarzan or Pocahontas shows.
With all that said, I will typically try every ride at least once, and for the most part every show. I will definitely give this show a chance, and I hope it's open in a month when I'm down there.