Oh, they have always been the darkest shade of grey in the Horde, for sure. And some of them have done undeniably evil acts. But as a group, they are still a shade of grey and not pure evil. Especially in the first few expansions, when they had the very understandable goal of revenge against Arthas.
It was heavily implied that they weren’t capable of true positive emotions, at least not for long. But there was a pretty wide range of attitudes among the NPCs at launch. Some had a sort of grim cheeriness about them, some seemed aware of what they had lost, and some were just kind of neutral, going about their new everyday lives.