The thing about copyright law is: it was created to prevent people from using other people's works, and selling it as their own or making a profit off it in some other way. In short: it was created to make sure that the only person allowed to sell content was the original creator.
Because physical copying was hard, this made sure that content-creators had a fairly secure income from selling their content. These days copying is easy though, so now the "offenders" are often the people that may or may not have bought the content, but managed to get a free copy now. This (arguably) leads to lost sales.
This is not what copyright was created to prevent though. In fact, if I write a scathing review of your work, saying it sucks and that every time someone buys it, God kills a kitten, I am probably costing you sales too. I am costing you money in exactly the same way that I would be if I was sharing your stuff. In fact, if I shared it people might conclude on their own that it is worth buying anyway, where as if they believe my review they will never buy it.
In short: people burning content to CD's and selling them: still very easily procecutable. In fact, they probably suffered the most from file sharing since that market just dried up. Why buy a knock-off now?
Customers sharing files? Maybe morally wrong, but unenforcable. Yes, it's sad, but with the advent of digital technology content creators lost an avenue of possible income. It's what happens though, and other ways have sprung up. It also created new ways to reach your customers, and provide a more personalized experience.
The world is changing, and those that don't change with it get left behind.