I disagree. The USA didn't do nearly enough in terms of repayments. The African American population suffers to this day--slavery is not as distant as it appears, it is really only a few generations old. The disparity is astonishing and old money definitely plays a major role in upholding our current upper-class.
Historically, here and elsewhere, affirmative action has shown to not work as it was intended. What affirmative action often does is produce an improperly trained workforce. This is why I believe the only true solution could only have been implemented right after slavery was abolished. Any attempt to directly transfer wealth will just bring problems on both sides of the equation--some will complain because they are not getting the compensation they think they deserve, or because they are not getting anything at all, while the "descendents" of the oppressors will feel their money should not be given away because they personally didn't really do anything wrong. This is why wealth distribution is very difficult and while I believe that from the moral perspective it should still happen I do not think it ever will primarily because the world is now dominated by a capitalist mindset.
However, in the end the USA and Britain are not the only ones at fault. Lack of proper compensation is a trend virtually everywhere. However this does not place the USA and Britain out of the equation. In fact, what many consider modern slavery--child labor--is used by major corporations that have originated primarily in the USA and Britain.
While it is true that universal reparations are virtually unconceivable I still think political correctness is only meant to touch the very surface of the actual problem.