I wonder if the high resolution screens make things worse, in that they tempt you to look at smaller things that you should be comfortable with.
While I understand what you mean about the risk of making things too small and then struggling to focus on them, that is far outweighed by the improved readability of text at high resolution. One shouldn’t be aiming to fit more on the screen, but to use scaling to use more (smaller) pixels to draw the same thing.
At work I now have two 28” 4K displays, with Windows configured to 150% scaling. And it’s gorgeous. Text is just plain easier to read.
They sure look good, but you have to focus better.
Our eyes always seek to optimize focus. Blurry low-resolution images cause eye strain precisely because our eyes are working hard attempting to find focus that
cannot be found because the image itself is blurry.
A sharp image (or sharp text) has high contrast and thus makes focusing easier, reducing eye strain.
Low light reduces contrast, which is why reading with insufficient light is tiring. (To the point that there are workplace regulations regarding minimum light levels.) Wildly excessive light is also tiring, but this is rarely a problem, since indoor lighting tends to be insufficient, not excessive.
A book tends to be lower resolution (even though it's printed at 600dpi or whatever, the text is low-res)
This is the diametrical opposite of how it is. Maybe you’re using “low-res” to mean something other than what it actually means.
(Talking about traditional offset lithography printing and direct digital press.)
Books are printed at very high resolutions: either 1270dpi or 2450dpi. Especially on good, smooth paper, text is exceedingly sharp. And because of how offset printing works, any microscopic jaggies that theoretically could be present get smoothed out by the time the ink is transferred to the paper.
Laser and inkjet, which are sometimes used for small-scale book printing (especially on-demand), while varying substantially in sharpness, are never quite as good as offset or digital presses — for text. (For photos, inkjet beats every other surviving technology that prints using ink or toner onto paper. Only silver halide is really superior, and dye-sub is no longer made in larger print sizes. But I digress.)
whereas a computer screen has many tiny things to attract your eye.
Are you referring to pixels, subpixels, or GUI widgets?