I am sure the people who would murder you in your sleep can easily come up with a similar argument. For them, murdering someone is not as morally heavy as it is for you.
That's just it though - murder isn't wrong because it's illegal, it's illegal because it's wrong. As far as moral conundrums go, that one's pretty cut and dry.
Copyright infringement is a much more complicated calculus.
True, but the problem is that while we can agree on what is illegal, we cant agree on what is wrong. So we "sign" a contract called law, in order to establish some common ground. So when I see that the contract no longer suits me( and I do believe that this is the case indeed nowadays with many laws), I consider it unethical to just breach the terms of the contract instead of negotiating a change. I still want others to respect the contract even if it doesnt suit them, don't I?