It's not the idea...it's the reality.
If the majority of people on the planet...or at least in this country...were of mixed race parentage, I believe that we would stop defining ourselves by one race or another. We would just become "people"...or "Americans" with no modifier...or "humans".
Are you willing to allow your daughters to marry and have children with a minority in order to take one step closer to thios utopian society?
yeah...didn't think so.
We already are mixed-race. Every one on this planet. No one is pure anything.
"Pure" europeans have a mixture of blood from Viking invaders, Vandal, Visigoth and Frankish invaders, Moorish invaders, Ottoman-Turk invaders, Cossack invaders, Mongol invaders, Hun invaders, and whoever else migrated or intermingled through trade with the Europeans.
So I find it offensive to allege, based on nothing, that Americans are "racist", especially since I've seen statistics to show there are more interracial marriages every year.
Another article I read said the last "natural blonde" will disappear in about 200 years, due to interracial marriage, and the fact that so many women artificially color their hair blonde, that anyone trying to preserve genetic purity of even that trait (not even racial purity) would have trouble finding a natural blonde to mate with. Although when the clothes come off, one can always see if the carpet matches the drapes.

In my case, I'm English, Irish, Dutch, German, Scottish and Cherokee (that I know of, from the last 180 years or so).