Q: Why Is The Business Model Of Buying Digital Content Failing?
I'm not sure you can say that it has been fully tried.
The problem with both music (plus movies) and books (plus other print media) is that in both cases you have entrenched interests who have made big investments in physical content production. Those investments were so large that only a few companies could control the process. Musicians and authors had little choice but to work through these large entities, and since that was the case, these same entities took care of many other aspects of the process, truly as a convenience to the content creators. The creator would sign with a publisher, who would not only use their expensive equipment to produce the physical product, but would also take care of copyright issues, monitor for infringement, cover legal expenses, arrange public appearances and so on.
Many of these services were, and are valuable to the content creator all by themselves, but were never unbundled from the one thing that content creator couldn't do on their own: publish.
The failure to unbundle these services is at the heart of the problem (or perceived problem).
Why does a digital version of a book cost almost as much as the physical form? In some respects (especially going forward) the digital form is superior, especially once you get over the desire to see it on a bookshelf or get your favorites autographed, etc. But we all know that the act of physically printing a book is a significant expense that we should see subtracted from the cost.
In order to satisfy content creators that they are still earning their money, publishers need to do certain things, but to satisfy consumers that they are not paying for the printing of a book or the cutting of a CD and having that money pocketed by some middleman, publishers need to make changes on that end as well.
One thing that Amazon has at least partially done (they and other need to go much farther though) is to remember what books you have purchased and make them downloadable again in the future.
When digital media finally replaces physical media, I'm pretty sure it will have the following properties: A purchase will be recorded in a database that allows at least a fairly large number of re-downloads of the content. I shouldn't need to make my own backup copies etc. I should be able to assign (give) my purchases to someone else. I should be protected from future format changes. If the content is PDF and that format is eventually replaced with something else, I shouldn't have to purchase a copy in the new format.
I've only scratched the surface (no pun intended) but I'm quite sure in the future digital content will be worth more, because publishers will do more to earn their keep, both from the perspective of content creators and from consumers. At that point, DRM, if applied, won't be a problem for consumers, but then again, it probably won't be needed either.