If only the publishers would let them do this with books!
I'm sure they will in 5-10 years. The ebook/ereader market is rather 'new' compared to the digital audio market, at this point everyone has likely already purchased a digital version of their music or pirated it so there won't be any lost sales (same idea for iTunes match and other matching/cloud services). It's interesting to see the music industry keep moving forward and allowing this type of stuff to happen (and t…
There is also a big difference in how easy/legal it is for a home user to convert the physical good to a digital good. Ripping CDs is trivial and legal. Ripping DVDs is illegal due to the DMCA, and ripping books is physically challenging. The larger the barrier to ripping, the more publishers can charge people to own both formats.