If you had to dig through menus to turn pages, I'd agree. But for me, an ebook already wins in terms of usability: it's thin, no matter how many "pages" the book is; I don't have to worry about small margins making it hard to read near the spine; I barely have to move a hand to turn the page, and when I do, I can do it one handed; I can hold the book one handed, no matter how thick; I can read at night without a separate light (which would cast uneven shadows).

As far as I'm concerned, my reader does just about everything better than a book. As I mentioned, quick flipping is still superior in printed books, but I almost never need to do that. Other than that, I find the usability great. Lesser-used features are out of the way, but accessible, and the thing I do most (turning the page) is superior to a printed book, as far as I'm concerned.

I'm all for usability improvements, but I'm not convinced a book is somehow more usable than a Kindle.