In an ideal world you would be correct and I hope nobody would disagree with your ideal desire (well, I know some do).

The reality, however, is still far from there. The point of diversity programs is not to accentuate the differences (although it can have that as a second order side effect), but simply to increase the rate at which these barriers break down. There are plenty of studies that show that people who are around others who are "different" (whatever the dimension: body shape/color, religion, political views, etc) in general stop being bothered by the differences. So it's in everybody's interest to try to get more of that. And in the long term it's good for business, even if it may or may not be in the short term -- but why should't corporations invest in the long term?