How important is unique content, really?

Interesting. I don't know what to make of this. I have a site that is just a news aggregator. It updates regularly and has been in the top ten on its keyword for a year now. At one point was outranking the sites that had the original articles and was just below the New York Times and ahead of Yahoo, the LA Times and others.

Reading this and other posts like it, I am at a loss to explain.