Knowing full well they suffer from a diabetes rate nearly twice that everybody else and they are probably sentencing many of them to death at a young age, Coca-Cola decides that blacks and hispanics are likely dumb enough to keep buying their toxic crap long after the former demographics have begun to peel off in huge numbers.
This is very similar to the tobacco companies targeting minorities with cigarettes when the mainstream began to wise up. Some people will do literally anything to turn a buck. They'd probably pimp their own mothers out if they thought it would improve sales.
The terrible irony about many of these shifts in marketing is that I have personally seen Yank companies that have lost all credibility on their native soil pick up stakes and move to Australia. This gives you a pretty good idea what the Americans think of Australia that they always know they can unload their worst junk on the people here. This happened with the thimerosal in vaccines when many Americans refused to give it to their kids - they sent all their stocks to the land of corkhats, knowing the locals down here are usually too drunk to worry about anything. They were right.