Because it was a means to transfer racial oppression to a separate but similar mode of production: slave labor becomes wage labor, white capitalist hegemony eats lust like bondage times. We work trades for their companies and we get pennies worth of our hard work that goes right to them...the minute we challenge that socioeconomic order, Nadir state sponsored terrorism like lynchings and private violence quell our fervor. That's the only reason they wanted it; they had to find a new way to continue racial oppression since the mode of production shifted from agriculture to expanding industry.