* A significant percentage of music is still only available on CD, and not in digital media. Until recently, music from one company (say Sony) was only available from their digital music store, which had their own player app with their own DRM. These things create significant inconvenience to the consumers, hindering the adoption of digital music.
* The music industry in Japan came up with a brilliant business model that enabled them to sell the same CD multiple times to the same consumer, basically by bundling a ticket to each CD. Sometimes a single ticket grants you one vote, sometimes you get one piece of (say 12) tickets randomly and you need to complete all 12 pieces to get something. This forces loyal fans to buy 10s and sometimes 100s of the same CD.
It's not like people are carrying around portable CD players any more, so these factors obviously creates a rapidly diminishing music fan base. I still hope that eventually the decline in the CD business will force the industry to wholy embrace the digial music, but I'm not holding my breath.