I haven't seen much evidence to the contrary that the music business is tanking. I don't really buy the disappointment with buying a crappy album argument. Radio stations used to play entire albums at launch when I was growing up. I might be disappointed with a track or two on an album but it was very rare that I would purchase a complete stinker.

His point that there aren't a lot of concept albums anymore where people listen to every track is an interesting one though there were hardly a lot of concept albums in the heyday of rock that those that were are very notable.

One issue that is not iTunes specific, but the ease that we can play digital music including custom and autogenerated playlists may also have something to do with it. With CDs and albums, there was a physical cost to jumping around and most of us were not ambitious enough to create mix tapes. Maybe just the convenience factor of accessing our existing libraries reduces the purchases of new music.