The Kansas-Nebrask Act was an 1854 bill that mandated “popular sovereignty”–allowing settlers of a territory to decide whether slavery would be allowed within a new state's borders. ... Kansas was admitted as a free state in January 1861 only weeks after eight Southern states seceded from the union.Oct 29, 2009
Answer: Because they were property.
Explanation: Slave owners did not let slaves keep their names because they were merely property that was constantly being bought and sold. If you don't have a name then you're seen as an object, people simply didn't feel bad for objects.