It’s called DRM—Digital Rights Management. It’s designed to protect media producers, whether they be writers or musicians or whatever, making it illegal for you to purchase something and then email it to all your friends so they have copies they didn’t pay the artist money for. In theory, it’s a good idea. Having an e-copy isn’t like purchasing a book in the store. If you loan that out, the person probably isn’t going to spend six hours at a copier to make their own book they didn’t have to pay for. Until DRM came along to lock it out, copying an e-book was just as easy as hitting Ctrl-V.
The only thing is, now you can’t even transfer it among your devices, or give your copy away. I get that piracy is a bad thing and is difficult to deal with, but in an age where computers and game systems last maybe five years before the new model is announced, it’s unfair to consumers to have to trash all their previous purchases if they want a new device. It’s especially sucky when Apple has been accused of price gouging with e-books and the new Xbox One won’t be backwards compatible.
Sadly, this isn’t going to change anytime soon, and things will probably grow more restrictive. Say goodbye to copying songs from your laptop to your desktop to your new laptop. If you break your e-reader, you break however many books you bought with it. Oh, and in the United States it’s illegal to try and get around a DRM scheme (seriously, that’s what they’re called). So have fun with that.