I have had this conversation several times since I wrote How to Write Like Malcolm Gladwell, and Gladwell takes a lot of flak these days, so here are some brief thoughts on why he has been so successful.
Have you read non fiction from the pre-Gladwell era? The mid-market list from the noughties, nineties, and earlier isn’t great. Whenever I pick one of those books up for research I am amazed how thin they are.
Social science research isn’t as conclusive as it looks. Most non-fiction gives an answer, some big solving idea that will change the world. Mostly it is way too specific and over generalised. Gladwell might not say this, but it’s his operating mode. He gestures and speculates beyond the strict research findings because he knows they are not the final answer.
Others like Michael Lewis are way more story based than Gladwell, who actually uses a lot of information in his writing. Gladwell is looking particularly good right now…
He has a lot of technique—syntax, style, etc—at his disposal and he uses it effectively. As well as being immersed in modern culture, he knows the Bible, and a lot of history—breadth not all of his competitors make use of.
Many important ideas have been spread widely by his work, and thus discussed more than they would have otherwise been. Isn’t that the whole ball game?
Gladwell has second & third hand knowledge that he gussies up. I got a PhD in experimental psych in the 1990's, so I know first hand some of the researchers who have been written up. Steven Pinker famously caught out MG phoneticizing eigen-value incorrectly, and diagnosed: "I will call this the Igon Value Problem: when a writer’s education on a topic consists in interviewing an expert, he is apt to offer generalizations that are banal, obtuse or flat wrong"
Consider his breakout, The Tipping Point, which absurdly advances the spicy argument that influencers can have an exponential impact on cultural fashion. Every midwit manager loved this notion, since it offered a virtually free lunch if you could somehow claim that your handful of customers included some dynamic hushpuppy amplifier. Logically, this can only be identified post-facto, and so it's just a circular argument that things that got very big had to start small, and the people in the first stage had inordinate impact.
John McPhee, Bill Bryson and Jared Diamond are authors from your decades ago time frame that generally hold up and write well. Gladwell does stand out.