I mostly agree with this, except that iPod was far from the only portable digital music device (mp3 player) — just like Kindle is far from the only eReader using eInk screens.

I think for music, some of us took a longer time to give up our mp3 players because solid-state phone storage was much more expensive than the mechanical drives that high-capacity iPods offered. But as streaming services became available, fewer of us felt the need to have a device that could hold our entire library. It became reasonable to store just the niche music (whatever the streaming service didn’t have available) on the phone. The prices of solid-state storage dropped over time, too, and most phones now have more storage than most high-capacity mp3 players did. Plus, some music streaming subscriptions let you upload your obscure songs into the cloud and stream them from any device. So the advantages of having a dedicated mp3 player became fewer and fewer. A few people still want them, but there’s just not a large market for them anymore.

With eReaders, things just haven’t gotten to that point. The battery life is indeed a key advantage over standard tablets — I’ve been known to occasionally exclaim “my book is out of battery, I hate the future!!” 😂 The screen itself is probably the biggest advantage, though. I can read it very easily in the brightest outdoor light (say, relaxing on a beach). Or I can configure the front lighting (which shines onto the screen, not out of it) to be very dim, just enough to read the page in bed with the lights out so it doesn’t prevent me from falling asleep. I can read in the pool or the bath if I wish, some eReaders are waterproof.

Perhaps someday tablets will be able to combine the screen technology so that it acts like an LED panel most of the time but can also switch into a paper-like mode? I’d be surprised if we still have lots of dedicated eReaders being made 20 years from now, but the tech definitely isn’t here yet.