Humans are already biased towards thinking that various positive characteristics are correlated with each other. Keeping track of an explicit "goodness" variable would make that even worse. So while I don't see anything wrong with comparing specific characteristics between people or groups of people, I endorse the norm that it is not acceptable to make statements of the form "Person A is better than Person B" or "Group A is better than Group B". "Quality of character" is nowhere near specific enough.