This is true but I think the ultimate test of a Hansonian view of human institutions (as of any view) is whether employing it allows you to make more accurate predictions and thus better decisions. It is my belief that learning about economics, evolutionary psychology and Hansonian-type explanations for otherwise puzzling human behaviour has improved my ability to make predictions. I do not currently have hard data to provide strong evidence to support this belief to others. Figuring out how to test this belief and produce such data is something I'm actively working on.

Ultimately it seems like this is what a rationalist should care about - what model of human institutions produces the most accurate predictions? The somewhat justified criticism of ev-psych explanations as 'just-so stories' can only be addressed to the extent that ev-psych can out-predict alternative views.