The sloppy reasoning/lack of substance are features, not bugs. He isn't a serious intellectual gladiator, he is a merchant who makes soundbites that educated, upper middle class people can use to sound intelligent and well read.
As long as people view them as such it is not problem. My frustration is when people cite Gladwell's ideas as either 1) the basis for strategic decision making at a business 2) the grounds for a major public policy decisions.
On a side note, I'd love to see this kind of breakdown for a lot of the shows on NPR, especially This American Life