Dual Disc

Bruce Sprinsgteen's new album is being released as a Dual Disc format with normal CD audio on one side and then DVD video on the other side. I'm surprised it took them this long to come up with this idea since double sided DVDs have been around for ages.

The only concern I have is that if this becomes widespread what will happen to the traditional concept of a music album?? - will video content become obligatory and thus will music artists end up being made more and more into video/movie stars?

Also why did we never see double sided audio CDs? For many years we've been getting double albums with 2 CDs in the one case. If this sort of thing is possible why did no-one ever invent a double sided CD, or if they did, why didn't it take off?

[Currently playing on my IPod: Still Here by Vertical Horizon]