Why don't we still have a good eInk reader device for research papers?
There are so many people in academia.


This is the crux: there really aren't. The kind of scale necessary to make electronic devices profitable is much larger than academia. There are about 2.5 million graduate students in the US, according to a quick google search. The sony e-reader sold about 800,000 devices and is considered a failure. About 20% of US consumers own an e-reader at all, but they might not like your specific device enough to spend $200 on it (graduate students are poorer than the average consumer, too). The likelihood that a device targeted at such a narrow market would approach anything like the necessary sales is very low.