What's wrong with the hat? Its got the whole cowboy feeling going.
There's nothing wrong with how it looks. It's the fact that Harry doesn't wear a hat in the books, yet is nevertheless always pictured wearing one in the book cover illustrations. We deliberately kept Harry hatless in the comic, and I hoped the same might hold true with Subterranean Press' adaptations, as the whole hat notion started with Roc/Penguin. Nope!