Dr. Mauser comments at length on a piece by David Gerrold (who used to write fun and imaginative stories, not all of them involving tribbles). This quoted bit demands a brief additional remark:
So, yes, it is inevitable that science fiction authors will explore that diversity — expanded roles for women, new definitions of gender and sexuality, the contributions of People of Color and other non-white ethnicities.
Look, when Heinlein did this stuff, it was boldly transgressive. When Star Trek, back in 1966, put a black woman on the bridge, with command authority over white men, it was transgressive - likewise, including the token Russian, the token East Asian, and the token bug-eyed pointy-eared monster.
But it's been done to death. Randomly pansexual characters? The protagonist whose race remains unspecified until three pages before the end (because, in Heinlein's world, race had nothing to do with the story)? Already been done, in ways that didn't break the storytelling. But we mustn't say that nowadays, because Heinlein has been branded a fascist (now defined as not-a-loyal-communist).
And the Trek franchise has long since gone utterly token-mad, with no end of implausible interspecies hybrids and other ethnic tokens.
What's more, Gerrold and the Trek franchise (among many others) are engaging in destructive Balkanization. Heinlein's female and variously-ethnic characters were, as a rule, strong, capable individuals. Lt. Uhura was a competent (within the TV context) officer who happened to be a woman of African descent. The new model?
In the new model, all the characters who aren't straight white men are defined by their differences, and those differences are expressed in ways that make them utterly unfit for any sort of job that calls for professionalism. It's one thing to have an officer who, when it doesn't get in the way of his duties, makes outrageous comments about the glories of Soviet Russia or of Scotland; it's quite another to have an officer who (on account of the way his ancestors lived four centuries earlier) has weird Visions at times of crisis.
This ties in with the "safe spaces" movement: the underlying assumption is that straight white men are so objectively superior to everyone else that they must be silenced and excluded in order for others to have a chance of advancement. And this is supposed to be progress?