Things have indeed gotten better, I'm not denying that, and the number of racially motivated killings have indeed slowed down. But they haven't stopped.
It is also worth noting that while Klan numbers have dropped, other groups are growing, various NeoNazi organizations like the National Socialist Movement, terrorist groups like Army of God, etc. Heck, there are nine people running for election this midterm with a decent amount of support with open ties to such groups. More than at any point in recent history.