I'd never heard "light skin" used as a (pejorative) noun, before reading your piece. That's definitely a racial microaggression for which I'll be on the lookout, from now on, in daily conversation.
Do you believe there is any value in using "light-skinned' or "dark-skinned" as an adjective or descriptor, when speaking about generic people in the third person in the context of discussing the effects of colorism within society? I'd think that'd be a much different dynamic than somebody who ignorantly refers to one of your daughters, directly, as "a light skin"?