[King of Snake]

that definition of theft is at least partly based on the assumption that there's a scarcity of the good in question. If you steal someone's car, that person loses his car. If you download an album, the artist doesn't lose that music, nor does the retailer lose a physical product (cd/lp).
The artist and retailer might have lost a sale if the downloader would have bought the physical product if the free download was not available. This is not certain though.
Just saying that with the current state of technology there is a definite grey area in the whole downloading=stealing debate IMO.
I can't claim to be completely on one side or the other myself. I've definitely downloaded music and software for free that otherwise I might have bought, but I do also buy a lot of music and software that I might not have bought if I hadn't downloaded it "illegally" first (I put that in quotes cause over here downloading music is actually still legal, but uploading isn't).