You want discretion for judges so that they can respond to the problems of their era wisely rather than rigidly applying the ideas of another time without nuance
Unless those judges themselves have a fondness for an imaginary "great" time, and will apply their reasoning in a way that just happens to fit their ideology.
Law is either rigorous or it's not. When I'm told that the law is against me but gosh darn it the law is the law, I grow resentful of the "discretion" reserved for some but not others.
