I gather from your comments that your moral code depends heavily on the rule of law. Many people don't base their moral code very heavily on the laws currently on the books, except as far as those laws reflect the original intent of law - to make the world a better place to live overall. It's generally agreed upon that stealing physical goods, murdering, etc. make the world a more unruly, unpleasant, inefficient, discouraging place for meek, cooperative people. Filesharing doesn't fall into the same league in those terms, so many don't really believe it's immoral, especially if one wasn't going to buy those files if there was no alternative. In that case, it's like happiness created from nothing. This other moral code makes the morality question a good bit murkier.
If filesharing undermines the creators to the point where they stop creating, will the world be a better place? In case you haven't noticed, we've had YouTube for years but the home-made movies are not on the same level as the ones produced by the major studies. Most indy bands are good, but can't reach their full potential without financial support. Filesharing undermines that whole system, especially because it would be near technically impossible to prevent something from being shared in all countries except those where the work is not being sold.
Good question, but the more important one is whether filesharing is doing that. This is where the question of whether someone would have bought something otherwise or not comes in.
Anecdotally, most of the people I know who fileshare just consume more now than they did, in a wider variety. Some of them have stopped buying stuff, but most of them haven't, and many went to Hulu, iTunes, Grooveshark, Pandora, etc. as soon as those became a good enough alternative.
You don't need to prevent it completely, that's putting your eyes on the wrong goal (though this seems to be the tack that they're taking). You just need to make the alternative as easy or easier and inexpensive enough to not think too much about if you're moderately well off. It's a stupid company that tries to force their market to act in the way they want it to, rather than finding a way to cater to them.
That's my understanding, anyway.