I've seen some comparisons to George Lucas now, and I will kind of jump in to defend Rowling by saying this: It's actually basically the opposite. It's widely agreed by Star Wars fans that the reason the prequels failed so spectacularly was because George Lucas had complete control of the project and surrounded himself with Yes Men who never dared to question him. The prequels were, for better or for worse (OK, for worse), truly his sole vision, which was not the case with the original Star Wars trilogy, where he was not allowed to run unchecked and he voluntarily dispersed some of his creative power to others.

Now here we have it the other way around. Rowling wrote the original books all by herself, and seems to have had little involvement in this POS other than signing off on it and maybe providing a basic outline at the start. Which I can't prove but suspect was probably her just telling the writers what their limitations were so the status quo would basically be maintained at the end.

Moral of the story being, with Star Wars the creator having control of everything leads to bad results. With Harry Potter, the creator stepping away from control leads to BAD results.