The Manhattan Theatre Club's production of Eleanor Burgess' “The Niceties” is a thoroughly enjoyable, thoughtful piece. Set at an elite university in the northeast, it is the story of a white, female, history professor and an ambitious, black woman majoring in political science. They meet to discuss the latter's paper on the American revolution, and the exchange rapidly takes them into discussions of race, privilege and generational attitudes. It gets ugly, and the premise that these sisters are on the same side in The Struggle rings hollow. Yet, somehow, it irritates because there was so much potential that went unrealized