Exactly! Regina just got away with it. She got away with killing someone just because he defied her. She got away with traumatising her son by killing someone he cared about. They had her murder this character we cared about and then showed no consequences for it.
Yes, he might be only one of thousands of people who she murdered. But we knew him, he was one of the good guys. And when one of the good guys are murdered there are supposed to be consequences. Those are the rules in these kind of stories. Murderers are not supposed to get away with it.
It looks more and more like Regina is not actually going to suffer any real consequences for her actions, and that is bad story telling.