Oh, I think you're right (and see what I said to Hope, above). It's quite clear that Rowling went out of her way to minimize Snape and diminish his character as much as she could. The result was only minor damage to the character, but major damage (imho) to her plot and themes.

But I do think it's true that she hates fantasy. Who knows; maybe she really did intend to subvert the genre?