At the end of the day, it's HER experience and she's the victim so she might as well get something out of the humiliation and at the same time, this interview is helping other girls facing domestic violence.
And really, pretty much every artist uses their personal experiences for their career in some way.

. Britney had "For The Record", Beyonce had her marriage, Amy Winehouse had drugs, etc. There's nothing wrong with it.
Chris has pimped the the incident even harder and publicly released multiple singles directly about the situation yet people just jump on Rihanna.
