I believe that God's Law is Good and Right. He established and defined what IS Good and Evil.
No one wants to touch it, so I will.
You are applying your real world believes (which I think to at least some degree I share) to a fictional universe. DnD has bunch of gods, each with their own alignment - so it's less about good or evil, but whose favour you are trying to gain. I am not terribly well versed in DnD, but I am pretty especially Lawful vs Evil has less to do with being "good or bad" in moral sense, but more of "control vs impulses". Laws can be good or bad. It's more about your character wanting to follow rules, or him doing whatever feels good at the moment.
That said I do agree that alignments as they are are rather troublesome and too open to interpretation. That's why I would prefer a different reputation system, if such was ever implemented.
