Done, and good point.
No, I mean that as far as foreshadowing and follow through goes for writing, she is one of the best there is, if not simply the best. She was good enough at it that people wrote books analyzing her books for hints through extensive textual analysis. And those books were correct at their predictions (for example, that Snape was 'good', etc).
Meanwhile, you got GRRM who's publicly stated that now that some people guessed something, he thinks he has to change it. That's literally the opposite of good storytelling, and sounds like something Vince McMahon would do. It means that her stories were to the point, had a lack of asspull reasons for plot reasons.
Her purpose built world is also interesting, but not good interesting. She took basically the opposite method of Tolkien, and instead built basically a Disneyworld facade: the world works because it's interesting enough with enough bells and whistles that you don't notice that Diagon Alley has only the front edifice built. Basically, her worldbuilding is subordinate to a story: she had a story to tell, and just added stuff to her world that was cool enough and worked sorta well together that you would suspend your disbelief about the world not working. This explains why all of her expanded universe stuff flops: the world created was never intended to hold another story, as it's a collection of asspulls around some cool things.