10% is far too little. Amazon is R&D'ing and manufacturing tablet/e-reader devices, handling payment/currency, and all the dirty work necessary to get the device in the hands of the customer in the first place.
If it was, there would be a healthy e-reader market with competing devices and choices for consumers, which would deprive Amazon of business leverage over content distribution.
Barnes & Noble had a brief moment of glory when their first Nook color tablet was cheaper, better and unlocked. Devs were selling rooted Android SD cards on eBay. If BN had opened up the hardware, they had a chance of gaining the scale needed to compete with Kindle. Instead, BN went the other way, locked down Nooks, created their own App Store with poor selection and the rest is history.
Apple has managed to charge premium prices for devices (enabling a market for many cheaper competitors) AND keep leverage on app/content distribution.
Digital publishing needs to separate distribution from payment. Convert "pirates" into "free logistics services" and focus on customers connecting more closely with authors. Why can't authors accept elastic (value-based, pay-what-you-want) bitcoin payments?
A big problem with the competing device market is that books aren't portable between Amazon and alternatives (but they are between the alternatives). So, if you've bought a number of e-books on Amazon, switching becomes much more difficult.
