Why doesn't American Idol give us real entire performances with all the background dancers?

They need to sing ENTIRE songs, instead of one minute glimpses. Also, since this was Michael Jackson week, Kris Allen could have done the entire "Remember the Time" with all the 2 dozen background dancers. They don't have to wear costumes like in the real music videos, but I could imagine Kris doing the entire performance with all the dance moves like MJ does in his video. That would be awesome.