> gender-associated cognitive differences has become so controversial, and why the “blank slate hypothesis” is the only one considered acceptable? This was an entirely different story when I was in college.

Because that kind of "science" was leveraged by many as a reason, with things like "you're a woman, hence..." or "you're a man, hence...", even though the variation within a sex is enough to explain many differences for individuals.

It seems that pushing a simpler hypothesis is easier than explaining statistics to the world.