"Slavery in America has been around for 200 years, why's this Tubman lady trying to free slaves now?"
"The emancipation proclamation was a century ago, why's this Martin King guy starting to complain about the way blacks are being treated now?"
"The US Gov't has existed for 250 years, why are blacks trying to become president now?"
Maybe I am a cynical person, but I think what you said is a terribly backwards way to think and part of why problems in America exist for generations longer than they should.