As much as I don't particularly agree with it, I think there's a very specific reason for not allowing these sorts of optimizations: control over the experience. It's the same issue with Apple iphone vs Android phones - I'm an Android fan because I have a lot more control over what I can do with the phone I purchased. I would never buy an iphone because Apple meticulously controls what displays on their screens. I think to a degree Amazon is copying a page from Apples corporate textbooks and ensuring when you buy a Kindle there's a specific and predictable range of experiences you will have. This allows a consistent feel, while still offering some flexibility.
Personally I don't find Amazon as dogmatic as Apple in this regard, so I don't let it get in the way of the experience, but I suspect that's why you don't see it. Nothing wrong with trying to push them over this, however. I know Amazon definitely listens to their customers more than Apple.