I quit using Kazaa when the lawyers got involved. But the attraction was never free music. Rather, it was access to the largest library of recorded music in history.
I play in a roots music band, and I often used Kazaa to search for material to cover. I ran keyword searches on "truck," "train,", "drunk," and other such terms, and came up with some great stuff, including a very cool, very old song called "You Drink Too Much" by a group called the Chicago Black Swans, of which Big Bill Broonzy was a member (according to what little information I could find).
These days I enjoy using iTunes for the same reason. The selection is certainly not as vast as what was available during the heyday of P2P -- I haven't found anything by the Chicago Black Swans. But that will change over time as the music industry in general acclimates to this new environment. After all, free of both the limitations of shelf space and the geographic realities of retail, there's no reason not to make everything available. Somebody will buy it.
Journalist Chris Anderson covered the exciting new realities of book, music, and video retailing in an excellent article (The Long Tail) in the October edition of Wired. According to Anderson:
Unlimited selection is revealing truths about what consumers want and how they want to get it in service after service, from DVDs at Netflix to music videos on Yahoo! Launch to songs in the iTunes Music Store and Rhapsody. People are going deep into the catalog, down the long, long list of available titles, far past what's available at Blockbuster Video, Tower Records, and Barnes & Noble. And the more they find, the more they like. As they wander further from the beaten path, they discover their taste is not as mainstream as they thought (or as they had been led to believe by marketing, a lack of alternatives, and a hit-driven culture).
As Big Martha over in D Block says, "That's a good thing."