Serious question: Are we mostly about science content? Or what?

One of the themes likely to run through my posts is a search for a clean and easy way to talk about what it is that science museums are supposed to 'accomplish.' After four full years of reading articles about learning in museums, and finding that the vast majority of them nervously conclude that people don't really learn the kind of science we render valuable on pencil and paper tests during their visits, I am left with a serious dearth of serious stabs at an answer to this question.

What I have found is some serious anxiety in the field, and a lot of serious money put into trying to figure out exactly how re-work science museums in order to create the causal link between a visit, and a 'better' set of science concepts. Perhaps this isn't the only way to conceive of public value to a museum visit?