In addition to that, the experience for reading while travelling is far superior simply due to the battery life.
E-readers to me are a good example of the Unix philosophy applied to hardware. Do one thing, and do them well.
Though in my own case, I have no use for a powerful tablet computer. Reading is literally my only use for the form factors. For someone who does need a "real" tablet, a separate e-reader might not be worth the investment.
I feel uncomfortable reading from a high quality OLED (iPhone X) or IPS panel (Apple MacBook Pro displays and an HP EliteDisplay) after reading for an hour or so, but when I open my Kobo Glo HD, I can read for hours without eye strain or feeling uncomfortable, even with front light. It just feels natural and doesn't make my eyes dry, forehead stiff or feeling exhausted. This is a study I'm conducting myself for 5+ years. So, it's enough of a data for me.
If you're not using displays all day long, you might not be straining your eyes much, and may not be feeling it, too. Try using some artificial teardrops (without any additives, preservatives or active ingredients). If you feel relieved after using them, you're simply unaware of being uncomfortable, then.
This may be a bit insane, but E-Ink displays feel less "artificial" to me, more "rooted in the real world", even if the content is exactly the same.
E-Ink with lightly amber front lighting is super cozy, IMO. I tried using IPS displays with a similar, very warm colour temperature - it just looks wrong and I get a headache.
I thought it may be caused by the "E-Ink = reading, LCD/IPS = Work" connection, but the cozy feeling is also there when using E-Ink as a terminal.
It's strange, IDK :D
Samsung's "The Frame" televisions get close to this, as do some smarthome hubs and smart picture frames, but I've never seen an equivalent standalone desktop monitor with these features.
Reading fiction on a 300+dpi OLED set to white on black is absolutely wonderful for me, and I can do it for several hours in a row, provided that the ambient illumination is not full sunlight.
Reading fiction on a 180ish dpi E-ink screen is fine but a little aggravating because changing to the next page takes so long. Not-very-black on light grey is not my favorite color scheme.
The screen (Kobo Glo HD) I'm using is probably one generation behind of current screens. It's on par with paperwhite 2 or 3 IIRC.
I can just zone-out and read for hours without noticing any lag, distracting refreshes (my Kobo does full/reversing refresh every 5 or so changes), and I prefer to any screen I've experienced until now, which were not low end, low-dpi screens of any kind.
Moreover, I'm very rarely buying paper books now. If I can find the title electronically, I just purchase it from the Kobo store.