“Why do some feel it is less okay to have a dating/marriage partner preference regarding skin color than hair color?”
They are both silly.
Besides, I hardly ever see my wife’s hair. She covers it with a hat or scarf!
I attended the wedding of an African American convert to a white born-Jew a few weeks before Pesach; her daughter, who converted separately, flew in from Israel where she lives with her husband, another white born-Jew.