I know what Miriam Margoyles means, I do a bit of an eye-roll at grown-ups only reading children's books - nothing wrong with reading children's books as well as grown-up ones, of course.
That said, I didn't perform in a film based on one of those children's books written 20+ years ago, so there's a touch of biting the hand that feeds you going on there with MM
I have never read a single word of a Harry Potter book, so my admiration for JKR is entirely based on her words and actions in support of women's rights, and her philanthropy.
She's also a highly successful author of children's books - and I believe grown-up ones as well but I haven't read any of them either - so good for her, but that's not why I admire her so much.