So what if they're collaborations? It's not like she simply writes the words; she's very involved with the musical direction and arrangements. She finds producers that she admires and shapes the sound of her albums with them.
It's not like she hires "hitmakers" like Bon Jovi or Aerosmith do, so she can have a big radio song on her album. Feel free to look up the name "Desmond Child" and you can see that some of those bands' biggest hits were co-written. And he's also worked with Kiss, for the record. Bon Jovi has been collaborating with Child from Slippery When Wet all the way up to their upcoming album this year.
Oh yeah, Bon Jovi also co-wrote "It's My Life" with Max Martin, the svengali behind N'Sync, Backstreet Boys, and Britney Spears.
And on Bounce they have several songs co-written by Andreas Carlsson, a Swedish pop guy who also worked with Clay Aiken, Celine Dion, N'Sync, Hilary Duff, etc.
Bon Jovi=NO CREDIBILITY.