Digital designers should find ways to create evocative and sensory experiences in their ebooks. I'm all for that; one mantra has always been to design an ebook so that a reader knows exactly what book is open at a glance (or at least after a page swipe or two). How? Some ideas: color (as ornament, not meaning); book-specific ornamental dingbats; attention to every controllable typographic and design detail.
Here's an article by Anthony Franco that lays out the case for caring about our readers: http://bit.ly/1HVS3Ai