The problem wasn't that they were black, not black enough, or too black. The problem was that they were wooden.
The issue isn't racism. It's writing craft.
It is thin characterization in a time-constrained medium that already tends to generalize aliens in order to illustrate points - not about them, but about - us. Klingons are violent because audiences are violent. Vulcans are logical because audiences are logical. Medics are humane because audiences are humane. Photon torpedoes go boom because audiences like booms.
Star Trek, like all science fiction, is not about predictions or correlations with reality. It's not about facts. It's about truths.
Don't miss the forest for the trees. It's not whether the Space Pope really walked on plasma. It's what we take from the knowledge - and what we discard. To say a myth has no value - is an indictment, not against the myth, but against one's own discernment.
The producers didn't need Troi and Crusher to be soft. Gates and Sirtis wanted to be soft. The scripts were not about realistic dispersions of psychosocial traits across a population - but simplified, clarified morality plays. Trek played with our comfort zones - showing Tasha admit, in a time of fierce anti-drug social agitations, that "Drugs make you feel good." Showing diplomatic leadership in a time of Terminators and Rambos, Russians and Reagans. Showing soft feminine power in an era of pantsuits with shoulder pads and Cybill Shepherds out-toughing Bruce Willises. And yes, showing whole planets of black people in a time of racial integration hypersensitivity.
Trek may not have done so with the sophisticated story arcs and hyper-realistic techniques we know today; but it does challenge our comfort zones even today. We're still talking about the implications in 2013 - almost three decades later. I would say, mission accomplished!
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