Before [Astounding Science Fiction editor John] Campbell, there was basically a single science fiction plot – a square-jawed hero gets miraculously transported through space or time, and there either gets involved in thrilling pulp adventures involving Martian princesses or encounters a series of metaphors for the writer’s own political views, and then either gets transported back to his home time/planet or remains for more adventures. Think Buck Rodgers, Flash Gordon, John Carter, Adam Strange. That was, to all intents and purposes, the entirety of science fiction before Campbell.

Campbell insisted on actual plots, and for his stories to be actually about things. He acted as a mentor to writers like Isaac Asimov and Robert A Heinlein, and would often suggest ideas to them – Asimov’s Foundation series came from discussions with Campbell, for example, and Campbell was also the real originator of Asimov’s three laws of robotics […]

The first ten years of Campbell’s editorship, he was the best editor in the field. But unfortunately, he set a baseline level of quality and left it there, never raising it, while other magazines like Galaxy started insisting on things like competent prose, and characterisation, and other things which Campbell never paid much attention to. Astounding/Analog was still, in 1971, doing the same thing it always had, even as writers like Harlan Ellison, Philip K. Dick, Samuel Delany, and Ursula LeGuin were all doing things which Campbell would never have approved of, even had he understood them.

Because the other side of Campbell is that he was a reactionary, bigoted, crank […] Campbell’s racist views had a stifling effect on his writers even in the 1940s – Asimov said that one reason his stories never featured aliens was because Campbell would always insist that humans were superior to aliens, because he couldn’t cope with a worldview where white American men weren’t the best, so the left-leaning Asimov just didn’t write stories with aliens in, to avoid the problem.

Andrew Hickey on Campbell’s legacy.

Ack. Long quote (with all apologies to Mr. Hickey), but interesting bit of history. It also… puts Asimov’s robot stories in kinda a… not “new” light, exactly, but maybe a more explicit old light…

I’ve heard it said before but it always bears repeating: So much of speculative fiction, be it horror or fantasy or sci-fi or whatever, is built on reactionary bigotry and aggressions both macro and micro. It doesn’t make the genres or even the tropes inherently tainted or toxic, but I think it means that–as both readers and writers, particularly from non-marginalized intersections–it puts an onus on us to be more critical and careful about how we produce and consume things.