Why do most commercials that depict interracial couples consist of a black man with a woman who is anything but black?

I think that by making any couple in a commercial interracial, it opens up their product to any race or combination. It's probably supposed to neutralize the subject of race. For the longest time, it would have been a white couple because the majority of the country is white and any other ethnicities would be advertising products specific to those ethnicities, possibly causing all others outside of said ethnicity to lose interest in their marketing campaign.