The very smart Lukas Mathis posed a question after the Kindle Touch devices were announced at the end of September that was, “If you were to design a piece of hardware that was only used for one single task, to read books, how would you design it?”
In particular he thought that moving the page turning buttons to the touch screen was a bad idea:
What’s the one single thing Kindle owners do the most? I’m guessing it’s turning to the next page. While reading a book, every Kindle Touch owner will do this at least once a minute, probably hundreds of times in a single session.
With a button, it’s simple. You don’t have to move your finger. You don’t cover the screen with any part of your hand. You push down a bit, and you get tactile feedback, a little «click» that tells you that you’ve successfully initiated a page turn.
Now, compare this to turning pages using a touchscreen. First of all, the Kindles don’t have resistive screens. This is usually an advantage, but in this particular case, it means that you can’t rest your finger on the screen. You have to physically lift it before you can turn the page.
And in response to not his original question, but the question at the top of the section I just quoted, the single thing that Kindle Touch owners will do the most while using it is hold it. And with a real book you can hold it by any of its margins without obscuring text. However, if you add buttons to this margin, then you now have to be careful how you hold it, for fear of accidentally hitting a button.
So, I’d say that Amazon did optimize the reading experience. Though, I neither own nor have I ever used a Kindle, so I could be completely wrong. But I always found the placement of the page turning buttons on the margins to be a strange choice.