Imagine if you could hyperlink as you handwrote notes, fluidly with the motion or gesture of the pen. As with text editors like emacs or *vim, you'd create new modes of thinking as you interact with a machine at the speed of thought, with the underpinning physical motions being too fast and too easy for conscious attention. Make wormholes from one part of the writing surface to a distant one, recording connections, asides, without conscious effort. No more than you expend on the shapes of letters, or the layout of QWERTY.
Instead, we're kind of stuck on the UX of "ordered sequence of rectangles", with some usability hacks to mitigate the severe limitations of this skeuomorphism.
Surely there must be some astounding low-hanging fruit here, in the UX of epaper handwriting as a tool of exploratory thought.