The author could have "intended" to write a book for the money. Or the author could have "intended" to write a book to piss off his neighbour. Or the author could have "intended" to write a book for the sake of writing a book. Analysis which attempts to discern the author's intent usually reveals the biases on the analyzer.

I think it's more useful to be critical of a text in a way that shows what the text is doing and how within a context. Texts take on a life of their own, especially after the author has passed. And as the life of a text grows, culture changes and so does culture's body of knowledge. It's possible to have a different reading/interpretation of a text throughout the life of the text, depending on the body of knowledge of the reader.