Since the actual Gates are actually just a bunch of orange-colored steel posts, the art must be in the symbolism. And for once I agree. The Gates, to me, symbolizes the Western elitist class.
For years and years these self-anointed progressives have distanced themselves from the core principals and traditions of our founding fathers. Whether it's multiculturalism, globalism, or relative moralism, the theories of the elitist class tend to disavow the notion that Western civilization generally, and the United States specifically, are preferable to, for example, radical Islam as practiced by a totalitarian state. So in one sense, the Gates represent the elite's long journey from the myopic Western mentality to the progressive global community. Each gate representing a racist, sexist or otherwise oppressive western traditional overcome, such as the pledge of allegiance.
And though the elite always trumpet their tolerance, their tolerance is not extended to people who disagree with them. Accordingly, these retrograde fascist imbeciles and their extremist propaganda are defeated with character assassination in lieu of ration argument. For example: most modern art is so undefined and ambiguous that it could truly mean virtually anything to anybody. But inevitably, only a handful of elite-approved interpretations immerge to be regurgitated over and over again. You have an alternate theory? Instant proof that you are not sophisticated enough to be "one of us". So the uniformity of the Gates parallels uniformity of the "tolerant and diverse" elitist views.
And lastly, this work of art is a grand self-parody of the elite mentality. Elites will flock to see it while plagiarizing the review they read in the New York Times art section to demonstrate their sophistication. Syllables and syllables will be thrown around breathlessly to describe, what amounts to, a very simple exhibit.