How do you load other eBooks onto the Kindle? Just add Amazon DRM.
Ebook readers have extremely high contrast/readability and are extremely energy-efficient, being able to display several thousand pages of material without needing to recharge. eBooks are a narrow product, but they have their own ways in which PMPs cannot compete.
If you read some of the Kindle discussion groups, you'll see people complaining about "no backlighting", and then a few days/weeks later they will be lauding the fact that it has no backlighting.
DRM is not to prevent other files from being readable on the Kindle.
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