Why call your opponent names and become emotional? It's not effective.

In what world does personal expected value versus expected cost of breaking the law ever become a good way to make moral decisions?

There are at least two counterarguments to this.

1) The law is written for precisely this reason. Most people do live by a cost vs benefit mindset, and the penalties of laws are generally tuned until people stop committing the crime. I wouldn't want to live in a world where the penalty for murder was only a week in prison.

2) Anyone who uses the law as a way to guide their own moral compass probably isn't very moral, because throughout history every society has had laws which are later agreed to be evil.