No comment on the race aspect of this, but advertisers, marketers, and salespeople have always benefited from making people feel unhappy. It's one reason so many people loathe them.
It's a very simple and common tactic you will see everywhere: Make the customer feel inadequate, then present the product as a solution to their inadequacy. You don't need to directly attack them as inadequate. You can simply present a scene, or situation and let the customer's own insecurities/lizard brain desires fill in the gaps to associate the product with a solution (e.g. a liquor commercial that shows a couple having a great time partying with friends).
I'm not buying a lot of this "motif" usage stuff, but if you want to speak entirely speculatively, I'll bite.
Marxism extensively argues that it is easiest to oppress people when you categorize them differently. An example would be how poor whites weakened the rights of free slaves in post Civil War America. Marx would argue the rich propagated racist beliefs to the poor whites who then limited the rights of other poor people. The end result is the poor limit their own democratic representation. Scientific Socialism is an essay by Engles (coauthor of the Commumist Manifesto) where he argues all oppression is based off of sexism (infantilization, dehumanization, objectification) and shows how the concepts of oppression are modified for race and class, so each group appears different but are actually the same. How this would apply to advertisers might be to preserve the status quo, or to make people feel bad to compulsively buy.
Not saying I agree with every aspect of those arguments, but it is a well documented attempt at answering your question.
