It's doubtful that the particular monkey cartoon in question actually caused mass outrage. A rising of the eyebrows, perhaps.
The New York Post knew what it was doing. It was selling newspapers. It was selling newspapers in a time when the newspaper business is in financial trouble. It knew it was going to get some major heat and criticism. While Sharpton, race-hustlers, race baiters, and the generally misinformed stalked about their front steps, people were more intrigued in buying and talking about the paper.
Of course major media seized upon it and thrusted a somewhat dicey and edgey cartoon to the front of the headlines in a faux outrage. White on black racism, perceived or actual, sells.
The color involved here was not black or white. It was green. Expect more "shocking" stories to come out of the troubled newspaper outlets.