Thank you for writing to NPR.org and excuse the delay in responding. We really appreciate your enthusiasm for NPR's programming, and the fact that you would like our programming available for download. One real hurdle is acquiring rights to all the music we include in it. It's expensive and to date we have not had the resources. To make downloads available directly from npr.org, we'd have to clear a bundle of rights from performing rights societies and the record labels or individual owners. Historically, npr has been able to acquire them for broadcast because there are fewer rights holders involved, and we benefit from a statutory license. As i am sure you already know, resources are always scarce in public radio.
First off, I certainly appreciate such an explanation from a place like NPR. Many organizations of such size would not respond at all, or simply say "Thanks, we value your opinion ... blah blah blah."
But read that again. They can't let us download clips of copywritten music. If you've read Free Culture, this just echoes what Lessig says. Fear of lawyers' letters, and the high cost of clearing rights, keeps legitimate use from occurring. And keep in mind, the clips of music that NPR plays (at least on ATC and Morning Edition) generate interest in that music. Letting people download those clips is clearly in the best interest of both the music label and the artist.
The current state of copyright, especially as it relates to the Internet, is sorely broken, in a way that benefits nobody but lawyers.