It was silly. It was a huge over reaction. JK rowling has done nothing wrong getting inspiration from Native American culture. Its what writers do. We get inspiration from history and mythology and fairy tales. Its one of the oldest traditions in writing. How many stories are based off Greek myths or Roman myths or Norse myths? J.R.R Tolkien based Lord of the Rings off Norse myth. This has been happening forever. And its ok. If no one owns an idea or a story then a writer does not have to ask permission to use it. It belongs to everyone.
At the same time I can understand why some people were upset with her though. JK Rowling's decision to include Native American's in Harry Potter has pulled them and their very real beliefs into her fictional world. Their beliefs are not a joke. And then there is the stereotype of the wise and mystical native to think about.
But if JK Rowling had not included them people would have asked "Why not?" so I feel like she was stuck between a rock and hard place. Could she had done a better job? Sure. Could she had pleased everyone? Oh hell no. Even if she had gotten an American to help her flesh out this new corner of her world she probably still would have done something or said something to offend someone. You can't please everyone. Someone will always find something to complain about.
What I find interesting is the air of entitlement coming from a lot of the people who have been complaining about her choices. I know Harry Potter has been around for a while and has been apart of a lot of people's lives for a long time but we do not own this story. She does. It's her world. If you don't like the decisions she is making then don't see the new film. But stop getting so worked up over a children's book. Do the new houses have bad names? Yeah. They're not as adorable as the British ones. But who cares? Seriously. Stop whinging. Its just a story. She doesn't owe you anything.