One could imagine hacking something like this tablet to have a true interactive Squeak like environment on it. Or, better yet, a Squeak-like environment designed from the ground up specifically for epaper displays...
Downvoters: yes, you deserve the truth! :-)
However, if you are using an emissive display in an environment with constant and even lighting, you can set the brightness correctly and it will be just as good. Many people in such lightning conditions configure their displays wrong and mistake the misconfiguration for an inherent disadvantage of emissive displays.
The surroundings might not be lit enough for the health of eyes. This is the usual case and one of the prime issues why dead tree books and e-paper tablets lead to weak eyes.
Cheap, modular, long battery life, effective.