An unfortunate catchphrase.
"Free" in English here has two definitions that fight with each other here: free as in speech and free as in beer. (We can refer to these with the foreign words libre and gratis, respectively.)
Libre: Information wants to be unfettered, uncensored, un-bowdlerized, unrestricted. IIRC this was the original intent of "Information wants to be free", and so far as information can be said to want anything, liberty would be it. The abuse of patent and copyright laws is naughty. Censorship is almost always more ugly than what's being censored.
Gratis: Information wants to be $0.00, and downloadable over the Internet. Nuh-uh. Like kra said, information wants to be valuable. Things that are offered gratis are usually a case of "you get what you pay for", but when people who produce information do it for the money, they can put more resources into it, and work harder. (Yes, I know there are exceptions.)
[/me hides his MP3 collection under the bed]
Oh, and hypocrisy is a bad thing, too.
So far we have:
- Information wants to be libre.
- Information does not want to be gratis.
- I want information to be gratis.
Why? Well, this is the Information Age. Most information can be easily duplicated, at little to no cost, without the expense of creating physical media for it. To sell a CD, or a book, one has to create an actual object to store the information, but to share an MP3 or an etext requires no such object.
Now to bring in economics: I mean supply and demand here. When there is a great supply of something, its price drops; when supply is scarce, the price rises. When demand is great, the price rises, because it depletes the supply. The Information Age allows a theoretically infinite supply, so by all means the demand can be infinite and the price gratis, right? Not quite, yet...
The people who create information are not infinite.
There may be a capacity for a functionally unlimited number of copies of a Metallica song, but the number of actual different Metallica songs is finite. (Thank God. ;) If Metallica makes their living by selling copies of their music, you had very well better pay for it if you want them to make more.
Now, suppose Metallica quits the music-making business, stops selling CDs, puts their lawyers out to pasture, and are never heard from again. Metallica songs are now abandonware. Copying them is still technically wrong, but nobody cares about that minor detail, because (in the States, anwyay) you're always innocent until someone cares enough to prove you guilty.