Less is more. They showed an appropriate amount of skirmish and chaos for what amounts to the Empire opening fire on a culture performing their funeral rites. I don't think there needed to be any more- they showed that Ferrix will not go down fighting, they showed Bix and friends being saved, they showed Cassian leaving successfully, and Luthen getting exactly what he wanted- a new soldier for his rebellion. I don't think there's much else that needed to be fought