@Tomp - Well it's hard to compare digital products to physical products since you don't have to create the item more than once for a digital good. Just because you didn't plan to pay anyway, doesn't make it any less "stealing" You can't use the argument "I was never going to buy it anyway" as a valid reason for stealing something.
And that still leaves two other arguments. Personally, I downloaded a lot of music and movies when I was a poor HS/college student and there was literally 0 chance of me purchasing them as an alternative. The lost profits argument just doesn't apply.
1: An album is available for $10. It is worth $5 to me. I don't buy it.
2: An album is available for $10. It's worth $5 to me. I pirate it and obtain it for $0.
The second set of circumstances is better for everyone: I have gained total welfare of $5 and no one has lost out. I don't see how this is worse than the first option, or morally wrong..
It isn't your right to choose the price you'd pay for something and then copy it if you feel so inclined. You either pay the asking price for a good / service, or you don't pay and don't enjoy the benefits of the service / good. This is why copyright infringement which subverts this system is illegal.
I'm sure that the artist getting a new fan, and becoming more popular for free is a very dangerous process indeed :-) ...
Even if you do think copyright is still appropriate, it needs to be carefully managed. In general, the purpose of copyright was never to ensure authors have some 'right' to control their work in perpetuity, as is commonly assumed today --- you can see that at work right there in the US Constitution 'To promote the Progress of Science and useful Arts, by securing for limited Times to Authors and Inventors the exclusive Right to their respective Writings and Discoveries'. There's some interesting discussion here http://rufuspollock.org/economics/papers/optimal_copyright_t...
I think most people underestimate the effect that file-sharing has had on our society. Music is so popular, not because of MTV, but because of napster&ThePirateBay&YouTube. If it weren't for these services, most people would probably listen to at most 10% of the music they listen to now, more likely 1%.