Authorial intent is irrelevant as far as a literary analysis of the text goes. If what you're analyzing is the difference between an author's stated intent and the effect, then yes, sure, go ahead and do so. But as a literature professor, I am teaching students to analyze the text in hand, and the author's stated intent is not a part of that text.

The book is a cultural artifact which has information outside of the text: the peritext, the marketing context, the mode of delivery to audience (hugely important in highly mediated children's literature), and yes, the author's stated intent. That package is a valid object of cultural critique. But the text is the object of literary analysis, and all of that extratextual information is not a part of it.