Be it white, asian, black. Not many.
Also tastes vary a great deal. Asians love the more classical Hollywood look, but people grew up with that may not be into it. They want to be distinct, they want to deliver different message(s). One needs to learn what the clothing is says.
In this case, her dress is a counterpoint to Obama's hard/business attire. Any one noticed he wears a white bow-tie with black suit? Now that's highly unusual, since men wear white bowtie only with tux. So he's making a statement. So does she.