2/ The need for editing. The most potent selection tool will remain the quality of the product. In the iPhone/iPad AppStore, Apple guarantees the overall technical quality of what lands on its shelves. Apple's primary motive is to avoid poorly coded apps that crash or, worse, interfere with the inner core of the iOS. No such things on Amazon. Once a manuscript is properly formatted (not very complicated), it's eligible for sale. That's where reality barges in. Many self-published authors insouciantly flog texts replete with grammatical errors and typos. Very few seem to rely on proper editing and proofing, this is the main divide between amateurs and pros. Editing is both a mandatory and costly process – but worth every penny. It is probably the most critical part of the value added by traditional publishers. In the digital world, it must remain a key component of the process.
"The new book publishing business is starting to look more and more like the software industry", en The Guardian.