A tragic coincidence

- that the skin tone of the nations that rose to global military/economic/cultural dominance was pale: the same skin tone that tends to result from not working outside, i.e., from being part of the upper classes.  It could easily have been different.  

Why does this matter?

Every culture bears prejudices toward the upper class (consider the polysemy of "noble" and "royal" vs. "common" and "vulgar").  And in any urbanized society, the upper class ends up lighter-skinned than average because they don't have to work in the sun.  But if, for example, black Africans rather than white Europeans had colonized the rest of the globe, the local pro-light-skin prejudice of the colonized cultures would have conflicted with the pro-dark-skin racism of the African global elites, likely leading to decreased prejudices (and more awareness of them) across the board. 

Instead, as the chips fell, local colorism and global racism have exacerbated each other for centuries.  Skin-lightening creams pull in tens of billions of dollars worldwide annually.  Most places in the world (albeit not all), it’s more fashionable - and will get you into more job interviews and less trouble - to have lighter skin.

Rotten luck, world.  Rotten luck.