Having grown up in that area of the Midwest, I largely agree with the author's categorization, except that "people on their way to somewhere better who got tired and decided this was good enough" describes a LOT of the midwest, not just Indiana. Significant chunks of Michigan, Ohio, and Missouri, most of Iowa/Kansas/Nebraska, etc.
If you read the history of westward expansion, "got tired and decided this was good enough" is literally true for how much of the area got initially settled (by white people)
I think the people who have found their "good enough" place to live have more down-to-earth personalities.
And people living in "the best place to live" places or "all the people who do X should live here" places have different personalities (not always good).