Like most have said, its about testing it out first. Thats what the internet is about IMO. I'm glad I downloaded the new Beastie Boys album before I bought it because I would never buy that trash. And I love the Beastie Boys, so if it hadn't come out on the internet first, so I could listen to it, I would have been very unhappy with the purchase. It was ok, but I may never even listen to it again, so I'm just glad I didn't buy it.
The other thing is just like I said with the latest B Boys, albums get released on the internet early. A lot of the times I will get albums months before they come out, especially in electronic music. So a lot of times, I just download it to hold me off, and if I still love it when it comes out, I buy it. There are exceptions though. I got that latest Crystal Method Album almost 4-5 months before it even came out in stores. So I was pretty sick of it before it even came out, but I did buy it any way even though I haven't really listened to it since I bought it.
Another example is the Velvet Rovolver album. Good stuff, but I'm not going to buy it. Sorry it just wasn't that good. I will, however, go see them live if/when they ever come to Denver. And I might buy a t-shirt too. IMO, thats how you get a good sense of the band any way, and thats where they make most of their money. Why pay $15-20 for a CD when its the RIAA and those stupid bastard bitches that are getting most of it.