How many times have you send the desire of having ways to organize your contents to
kindle-feedback@amazon.com? Continue to regularly voice your desire at that email address. It is not a black hole. Amazon really spends time reading customer feedback.
As a user, I share your frustration. As an engineer, I want to scream because engineer does not make what gets to be on a shipping product. As an Amazon shareholder, I understand company direction requires careful planning. If there is finite resources, should that be allocate to make more books available for Kindle or make organizing features. There are trade-off everyday. Voice your opinion repeatedly to make sure Amazon hears what's important to its customers.