Christina Aguilera's problem is she doesn't have a lock on any niche in the pop game. She changes TOO much with each album and as a result, loses the core fanbase she built with the previous record.
So when she did 'Bionic' after 'Back to Basics', it looked extremely try-hard, desperate and out of nowhere.
She also has a huge reputation for being a bitch and I think that's why many aren't really "rooting" for her.
Her discography also isn't really memorable, despite her fantastic voice. She's known for her voice, not really known for her material, though she does have some really good tracks.
She'll never be as big as she once was or really truly compete with the current pop gerls, but she has her place in the industry (singing tributes and covers).
