Is legalise ethical and/or detrimental to our society?

There are several limits to using plain language in the criminal law. First, there is a constitutional rule regarding clarity. A penal law must be sufficiently clear so that a person of ordinary intelligence who reads the law may know if his proposed conduct is prohibited. The same rule requires that it be clear enough so that cops know what is prohibited. The same rule requires that a jury be instructed on the elements of a crime so that a reviewing court may determine if the evidence, applied to the law in the instructions, allows the conviction. The other limitation is that your notion of common sense is neither common non sensible. Murder is bad but there must be a definition of murder so that we might all know if this particular killing is one of the bad killings or one of the allowable killings, or a lesser form of killing. So, if you despair that common sense is not common or sensible. keep in mind that if might be you who is uncommon.