The undergrad majors at Yale University typically follow lukeprog's suggestion -- there will be 20 classes on stuff that is thought to constitute cutting-edge, useful "political science" or "history" or "biology," and then 1 or 2 classes per major on "history of political science" or "history of history" or "history of biology." I think that's a good system. It's very important not to confuse a catalog of previous mistakes with a recipe for future progress, but for the same reasons that general history is interesting and worthwhile for the general public to know something about, the history of a given discipline is interesting and worthwhile for students of that discipline to look into.