It actually is very relevant, if you live in the real world. Police would not treat the above example equally would they, they would come down harder on the man who beats his wife 5x a week It's not completely fair, but that's the way it is, because police resources are not unlimited.. The police would make a call, which one poses a greater threat to the public.
Similarly you will face greater punishment if you are caught with 20g of Cocaine, than if you are caught with 1g. It's not so much excusing the criminal, as putting things in perspective.
Both are still crimes. "He didn't beat her that much" is the shittiest defence I have ever heard.
Both are still crimes. "He didn't beat her that much" is the shittiest defence I have ever heard.