Often they were doing the best they could. In early Texas the settlers were confronted by the Comanche, who were probably the most formidable of the Plains Indians. It took General Sherman himself to subdue them, by methods he perfected in Georgia. You didn't sit down and reason with a Comanche. The samething was true of heretics like the Cathars, whom the Catholic subdued not by persuasion--although St. Dominic tried--but by main force.
Here's you problem. No. They did better than that. They did better than any other court system in the world they could read about or experience. That's an important historical distinction from "they were doing the best they could."
These guys advanced the cause of human rights and justice. And to the extent they appear barbaric: that was the extent to which they were unable to rise above their times, not the extent to which they subjected their times to otherwise unknown hardship.