I agree that surveys and the like will only tell us what people think, and not what they should think. But I'm thinking of philosophy as part of science here. Conceptual analysis is an important part of science, just as it is in philosophy. If you're going to study speciation, or gravity, or HIV, then you have to answer questions like "what does it mean for individuals to be of different species?" and "what is mass?" and "what does it take for someone to count as having AIDS?" Philosophers are asking "what does it mean for something to be right or wrong?", and the methods we have for answering these questions are basically all the same. Of course, scientists don't need to have correct and complete answers to those questions to do all their research, but analyzing the weaknesses of particular approximate answers that people use at a given time is an important part of the methodology sometimes. It's just that in philosophy, it's central at almost all times.

And yes, I think that the issue about the normativity of epistemology is one of the most important ones for showing people that they really are committed to there being some objective norms, regardless of what sort of moral skepticism they might think they're committed to. Once they admit some sort of objective normativity, then moral realism isn't any more spooky (though of course, it doesn't get any direct support from realism about epistemology).