What happened to the development of e-paper technology?

I've owned and e-reader for half a decade now and shortly after the technology first came out, there even were demos of colored e-paper tech.Nothing much has happened since then. Sure the displays got slightly better and have a faster refresh rate now but we're not seeing any ground breaking new products like e-paper smartphones.Where did the innovation go?There was the yota phone and there are screens you can clip to the back of your phone but expect for the light phone 2 (which sounds more than questionable), there aren't any phones that primarily use e-ink tech.I can't find any recent demos on youtube either, the newest developments are over a year old already, so it really feels like no one is pushing this at the moment.Does anyone have any insight to what the difficulties are and why companies don't seem to be into this all that much except for normal e-readers which are all kind of the same products really? via /r/tech https://ift.tt/2HDgAQM