OK, "there are studies?" Where?
Let's have some background here: The inverse color scheme (black letters on white background) that Apple has forced on users for decades is a vestige of the failed late-'80s/early-'90s attempt to make the screen an analogy for a piece of paper. Remember the "desktop publishing" craze?
The analogy fails because a piece of paper doesn't emit light, while of course a screen does. A white background on a computer is akin to reading text off the surface of a light bulb all day.
Every other major computer GUI except Apple's allows users to set up their own system-wide color scheme. Windows has had this capability for over 25 years.
Before GUIs, most computers had a hard-coded color scheme that presented white text on a dark background, to ensure the best readability. The background was often dark blue; to this day there's a checkbox option in Word to activate this very color scheme ("Blue background, white text").
Over the last few years, software publishers have finally taken matters into their own hands to give users a more sensible background than glaring white. Adobe, for example, has darkened its interface to charcoal. Color-critical applications (even some of Apple's own) have always used a dark-grey interface with white text.
Should Apple move into the '90s and offer users a choice? Of course. But that's not how Apple works. But if you want to talk about a bad move, it's clinging to a discredited and glaring color scheme that has us squinting into backlights going full-blast in our faces all day.