Still you have to wait for the page to render. When you are turning a page in a book or a printout you are doing something that requires some kind of activity from your part, but when you have clicked the button you are just waiting for things to happen.

I don't mean to say that this is a big problem, and I haven't been using E-ink readers that much. But when it comes to digital reading, I appreciate the snappiness of scrolling fast through pages and also the "jump to" functions, whether it's via links or "go to page" actions.