One of the inherent problems with American Idol as it currently stands is forcing the singers to do songs that are out of their comfort zone - having rockers sing country, or country singers do rock. It is a weak point and often after one of those shows, they get voted off.
Not every singer can do rock/country/Motown/gospel/pop/rap and big band classics equally well. Nor should they, but that is the basis for this show.
I don’t think any of those great singers from the past could have done all of those genres of music equally well, and that would have been it for them on the show.
Forcing these singers to stretch is not a bad thing, but when it comes down to voting, it was pretty easy to vote off Kelly Pickler after she tried to be the rocker lady.