I used to have a Kindle. Eventually it broke. Kobos seem even less reliable, my wife has been through 4-5 of them so far.
After my Kindle broke I switched "temporarily" to using the Kobo app on my iPhone to read. Although the form factor isn't ideal for reading, it's just so convenient that I never bothered buying another eReader. It also has all the advantages of a modern smartphone: touches to turn the page are instantaneous; controlling brightness is familiar and easy; I can copy and paste text into Safari to search anything I'm interested in. About the only environment where an eReader wins is bright sun, and well, I live in Northern Europe.
So yeah, I think I would say, although they're a nice idea - eReaders just aren't strong enough in their own niche to beat out smartphones for a lot of people, which means that niche stays pretty small and prices stay quite high?