If paying reparations would buy racial amity, then the descendants of slaves would be complaining only because they didn't receive a cut of their ancestors' sale price. Reparations can't change the past.
Wouldn't acceptance of money by blacks (however the law might qualify them for the benefits) amount to approving of the sale of their ancestors, as long as they personally profit? Again, this doesn't change the morality of slavery, though it might be argued to address the economic wrong, but at the cost of involving the current generation in approving it. Accepting payment would be like agreeing that the slavery, or the sale of a human being (legal at the time), wasn't a moral wrong, but there was an economic wrong in not providing some portion of the money for the slaves and their potential descendants.
The reparations are sometimes presented as justified because the slave-owners and some businesses profited from “free labor” and “got rich.”