I am only guessing obviously, but I would say she wrote it to be cleansing for her and for closureI am getting tired of this woman already, and I have not read any of the relevant books.
I don't approve of Job's parenting (as described) at all, but that is besides the point - we know he was a jerk. And, that he made so many stupid decisions that literally killed him too soon, especially considering how much health care he had access to, as a rich man. Almost like a death-wish, and pancreatic cancer is a death sentence even in this decade.
She couldn't have written such a book when he was alive, I understand that dilemma.
The picture she is painting of herself now is that of a very sore winner, bitter even after this many years. Her claim of having forgiven him to heal herself sounds false, as she seems to be still whining. I doubt he can defend or explain his behavior if he was alive, but now that that chapter is closed, what is her end-game here!
She obviously didn't write for you, but for herself to unload the burden she carried