I got Diablo II and Lord of Destruction expansion back on December 2004, and after the new Diablo Music player was made available, I enjoyed listening to the music.  That prompted me to wish to download them.  However, when searching the Public FTP of Blizzard, I noticed the MP3s were removed.  Furthermore, noticed all MP3s of all Blizzard games were also removed from Public downloads.

I posted at the official forums of Diablo II, requesting info.  This is the reply from a representative of Blizzard Online Support:

Medievaldragon: The Diablo Music Player is awesome. However, I would like to download the mp3s to play locally, and adjust the volume.

1. Are the MP3s available as download?
2. If not, would it break the EULA/TOS to extract the MP3s from the MPQ?—I don’t know how to do that, but It would be good to know if it is ok or not recommended.

NickJS: Unfortunately the MP3’s are no longer available for download. Extracting the files from the MPQ is not supported, but as long as you do not sell/distribute our files, it would be okay.

It seems the only way to get the MP3s of all Blizzard games currently is either purchasing the Soundtrack CD or extracting directly from the MPQ following the condition above.