You're so right. Additionally, I would put Stalin's purges, the Maoist's purges, Pol Pol's and Hitler's genocides, and on and on throughout history, on a long list of more repugnant atrocities.
Peoples have been capturing and keeping slaves throughout history. It is a time worn, if not time honored tradition. The Isrealites were alternatly keeping and being enslaved. Native American tribes kept slaves, captured from other tribes. Egyptians, Chinese, Romans, Babylonians, Greeks, Persians, you name 'em, they kept slaves.
I have difficulty seeing the importation of slaves (which ended in 1810, in the United States) or the keeping of slaves (which ended in the United States in 1865) as anything even nearly on the list of "greatest crimes". Don't forget that the nation was only 34 years old (or thereabouts, give or take a few additional years of unplesantness with the British Crown after we actually declared independence) when it made importation of slaves illegal. And the nation was only 89 years old when it foreswore slavery, as an institution, in its entirety. The continent of Africa has yet to foreswear slavery, entirely!
Not for nothing: but why is that? What makes slavery in America a WORSE crime than the THOUSANDS of years of slavery that preceded it, or for that matter the slavery that has been practiced in other countries since american abolition and to this very day?
Simple: because America, unlike any country before us, was dedicated to the idea of freeedom. To those whom much is given, much is required. We were and are the greatest country in the history of the world - not because we're the richest (which came from freedom), and not because we're the most powerful - but because we're the free-est! We knew all along that liberty was more precious than safety or comfort. Many knew at the time that slavery would need to be ended, but they lacked the political power to end it in the 1700s. It took another 80 years and the deaths of a heck of a lot of white men to bring freedom to all - and I'm extremely proud that America was willing to pay the price.
Bush's 'apology' isn't a sign of weakness - it is an admission that the road to freedom is difficult, slowed by human error and painful to travel - but infinitely worthwhile! It is a sign Bush understands how wonderful the goal of 'liberty for all' is. I'm proud of him and his statement.