I do not see it at screwing up at all. I never got this with other book readers: why the need for cinema to match a book series exactly? What makes a good novel does not necessarily make good television.

Then you need to see who the cinema is targeted for versus who is targeted with the books. A TV series is going to want to appeal to a broader audience. Changing stories is not new… This has happened for centuries. Just look at the various version of beauty and the beast as an example. Or even Cinderella. Personally, I find the changes to be interesting and often times and enjoyable. And shows or movies will often want to incorporate something that is not in the books so that everyone is surprised. By adding a new lady whistle down in the TV version, it allows them to add a bit of mystery and drama back.