You make very compelling points here, Allison. It's like advertisers are trying to show how "down" they are. For some reason, they seem to think highlighting interracial couples (where one partner is always white but the other might be Black, Latinx, or Asian) signals that the product being sold is used by people who are modern, edgy, hip and not the same old traditional fuddy duddies.
I think the issue is that advertisers (and producers of TV shows and movies) fear that not having a white partner means that the majority white audience won't identify with the couple at all. But the commercial success of movies with no white leads (and sometimes only a white sidekick, like in Black Panther) should reassure those folks. Audiences are hungry for good stories. They shouldn't stick in a white hero just because they fear the audience won't show up.