Of course they changed things. It's 15 books. Too much source material. It would be impossible to televise the whole story.
With that said though, I'd agree that some of the changes weren't warranted. They could have condensed and retold things without some of the oddities they introduced. For instance, Perrin having a wife and killing her the way that he did really bugged. Plenty of things I didn't like.
Fans have been wanting to see something on the screen for decades and this was the best attempt yet. I would have loved to see it through, warts and all.