Earlier quoted context omitted.
I don’t know that there is any technical reason why e-ink can’t develop a better refresh rate to match what we are used to, at least theoretically. I don’t think its refresh rates are capped in that way. The real problem is cost of course. Part of that is e-ink is still governed under a patent you must license and pay royalties to if I recall correctly
Eink works by physically moving bits of material around in a viscous liquid. You can refine that (use stronger electric field, stronger reacting pigments, less-viscous fluid, thinner layer for smaller travel distance) but never get around it.
I suspect that the current technology works by "setting" in place whole regions of the screen at once, and that this kind of process is inherently slow. Maybe in a (not so distant) future it'll be possible to have individual pixels changing, in a similar way as an mp4 doesn't update all the image when not necessary.
Or not. So many technologies just embank somewhere and find their niche.