Whenever anyone has the audacity to adapt a book for the big (or small) screen, they're inevitably met with blindfolded accusations that the book did it better (even from those who haven't seen their interpretation). It's just the way of the world. And of course, when those film-makers dare to change the source in any way, there's usually a pitch-fork carrying mob ready to crash through their door.
It's inevitable really, because you play a dangerous game messing with anything that has inspired a fanbase to love. Even when there are flaws in the source, you aren't actually allowed to aknowledge them: you simply accept them and adapt as direct homage. Otherwise, you end up being accused of making it worse with your own foolish decisions.
But occasionally - even with franchises as beloved as Harry Potter - film-makers taking liberties can lead to positive results. They can bring an objectivity to the creative process that actually improves on the beloved original. And though it might be hard to take, you're allowed to love those new bits just as much as the stuff written by JK Rowling's own hand.
Because sometimes, messing with the source can actually be a good thing...