Book paper is too rough to wipe your arse with, and if the publisher used cheap ink, you end up dirtier than you were to start...
Blame the publishers for DRM. They're the ones who refused to let Amazon sell electronic versions of their books without it. The Kindle is perfectly happy to display un-DRMed ebooks in any of the formats it supports. KDP, Amazon's self-publishing programme, allows the author to choose whether to add DRM to the book. I've left it off all of mine, for reasons that will be familiar to any Slashdot reader.
It's the same with regional restrictions. Traditionally, authors usually license their books to publishers by territory and/or language. An author in Germany might license his book to a German publisher, but that publisher might only be allowed to sell it in Germany, or only in countries where German is the main language. They might not have the contacts or the understanding of the market to do a proper job of selling the book in other countries or languages, so they're happy to let the author or his agent try to license the book elsewhere. Amazon.de carries the German version of the ebook, which the publisher isn't allowed to sell outside Germany.
The reason that terms from the publisher's contract with the author get carried over to the retailer is because of something called agency pricing. When selling ebooks, the retailer acts as an agent of the publisher, not an independent entity. The publisher sets the retail price of the book, and the retailer takes a fixed percentage of that as commission. This is something that Apple strongarmed the publishers into doing, because they didn't want to have to compete on price when they started selling ebooks. Google "ebook price fixing lawsuit" for more information. (Agency pricing itself isn't illegal, but the lawsuit alleges that Apple and five of the big six publishers colluded to use it to keep ebook prices artificially high. Some of the publishers have already settled, and have agreed to stop using agency pricing.)