Now, we are social animals, and we grew to value these thing for their own right. Societies valued strength and bravery, as virtues, but I guess ultimately because having brave strong soldiers made for more food and babies.
So over time, we tamed beasts and built tools, and most of these virtues kind of faded away. In our world of prosperity and machine power on tap, strength and bravery are not really extolled so much anymore. We work out because it makes us healthy and attractive, not because our societies demand this. We're happy to replace the hard work with a prosthetic.
Intelligence all these millenia was the outlier. The thing separating us from the animals. It was so inconceivable that it might be replaced that it is very deeply ingrained in us.
But if suddenly we don't need it? Or at least 95% of the population doesn't? Is it "ok" to lose it, like engineers of today don't rely on strength like blacksmiths used to? Maybe. Maybe it's ok that in 100 years we will all let our brains rot, occasionally doing a crossword as a work out. It feels sad, but maybe only in the way decline of swordsmanship felt to a Napoleonic veteran. The world moved on and we don't care anymore.
We lost so many skills that were once so key: the average person can't farm, can't forage, can't start a fire or ride a horse. And maybe it's ok. Or, who knows, maybe not.