There's plenty of laws like that. They're a statement about what someone oughtn't do in the hopes that people follow it simply because it's the law. I think it's a good solution to the situations where we want to establish a norm but it's beyond the scope of government to enforce it.
Assuming laws require enforcement is the secular version of "if you're an atheist and don't fear eternal punishment in hell, why are you good?"
The legal system is partly the codification of society's views on what constitutes unethical behaviour. Specifically, things that harm society as a whole.
Making an action against the law expresses a very strong disapproval of that action.
Assuming laws require enforcement is the secular version of "if you're an atheist and don't fear eternal punishment in hell, why are you good?"