why would anyone buy an eink kindle anymore?

I got one because I wouldn't want a tablet, I wouldn't use it for anything other than reading. An ereader is much less expensive and much better for reading.

Simple: no other kind of display screen is better suited to reading books with.

E-ink screens remain clear to read in bright light, have an antireflective screen surface, use very little power so I can take mine on a two week holiday and never need to charge it, and they’re lightweight. Unlike laptops and phones, an e-ink screen is not polarised, so also remains fully readable whilst wearing polarised sunglasses.

My phone or laptop both eat battery power ferociously, have reflective screens, are nearly impossible to read in bright light. There’s also the fact that if I’m on a beach then I don’t want to worry about my phone or laptop being stolen when I go for a swim.  I have no such worries when I take my oldest, simplest, battered but reliable basic Kindle with me. 

I have a Paperwhite beside my bed for nighttime reading, plus a Kindle Voyage in a nice protective leather origami-fold case which I carry around with me whilst commuting or travelling for work.

I couldn’t see the point of an E-ink Kindle until I bought one. After that I couldn’t do without it. I also have a single Kindle Fire which is a far inferior reading device in general but has one single advantage: because it has a colour display screen it’s the only Kindle I use when I need it for Illustrated cookery books and other illustrated reference books.

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If you are reading a book on an e-ink device, it's much easier on the eyes than a backlit tablet!  I can read a whole book this way, something I can't do with my tablet!

cause they like them

E-ink technology is used in the Paperwhite. Nothing wrong with the paperwhite, it's perfect for me.