I really don't like the "big star" panel either. I really don't feel like they have anything to add at all.
I think Idol worked at first best because the panel proved itself and its opinions over time. People grew to trust their opinions and insticts.
The panel for the years starting after Paula left were nothing but a celebrity panel with careers of their own to pimp. I found none of them interesting. TBH, I thought the first terrible idea was "Ellen"! I felt she was proof positive that they were choosing a panel for ratings and "promotion of celebrity-brands". And that is when it became obvious that these peoples opinions were not to be trusted cause they were not there to find a star, they were there to promote themselves... (and I like Ellen, but she was a terrible choice)