You make an excellent point: why does it make a difference today whether our distant ancestors owned slaves?  It seems unfair, and I agree it will perpetuate the animosity.   There are real issues to discuss, if we could just see each other as people, with 'people' problems, some our own making, some not.  When I spoke up in the restaurant, the whites expressed amazement, but at least the waitress 'saw' the Black woman and waited on her.  Of course if were no Blacks present, there would've been nothing to protest.  I think the years since then have made a difference.  Maybe we are having the national conversation  we need.