In regard to brightness, I agree that modern monitors are way too bright. The U2413 has 350cd/m2 at 100% brightness and about 120 cd/m2 at 20% which is still too bright for me. I usually need below 100 cd/m2. And I don't work in a dark room. And monitors are always calibrated at some very high brightness, so if you use very low brightness you get a bad picture. I searched for "low brightness" monitors, but I didn't find anything good.
My opinion on manufacturers. I know there is a petition out on this page to signal the manufacturers that some people have problems with eye strain. The problem I see is that it is impossible for regular users to define the technical cause. The only solution I see is: we either categorize types of eye/head problems and draw up a list of acceptable monitors/GPUs etc. or we wait till developers modernize their desktops and hopefully stumble upon this issue themselves.