Why not an Android based e-reader with a simple stand and a Bluetooth keyboard? Lighter, better for reading and enough if what you want is simple writing. And most probably cheaper. You can even have one with a stylus for handwriting.
I believe creating an e-ink device is, in many ways, a new category of devices that requires changes to the hardware, software, and many other areas to create a cohesive experience for people.
In the long term, I see it as a process of creating an ecosystem of e-ink devices that is open-hardware and open-source.