I think that there is much to be said here about a cultural and national identity present in America regarding how the underclass is perceived. Certainly, one can point to the period in American History of how industrialization created both "titans of industry" as well as some of the most impoverished conditions on the planet. Perhaps, it can be extended to today when Americans have to reconcile the fact that in a capitalistic configuration there are distinct "winners" and "losers," and that in some instances, the success of the former is directly contingent on the failure of the latter. It is right here where I would broaden the discussion. I don't see this as a particularly American cultural and national identity issue. I think that any nation that is committed to capitalistic ventures and the marketplace of free enterprise is a realm where there are distinct individuals who are successful and must relate this intense level of wealth with those who lack such material possession. We can see this in nations like England, Brazil, India, or France. I don't see it as much as an "American cultural or national identity." In a more globalized world where economic competition has been defined by what Zakaria has called, "the rise of the rest," the same endemic problems that Le Guin writes of in the 1970s can now be applied to other nations that are world players in the marketplace with the same effectiveness. Essentially, any nation that features intense and ostentatious levels of wealth and material prosperity that exist near the conditions of squalor and poverty would be able to have LeGuin's work applicable to their condition.
In her introduction to her story "The Ones Who Walk Away from Omelas," Ursula LeGuin wrote that her narrative was inspired by William James's formulation of pragmatism. She states that her story was written as an allegory of the scapegoat as the "dilemma of the American conscience."
In one criticism that is cited below, the author contends that LeGuin has never stated the problem. So, it is left to the reader to decide. Who or what is the scapegoat? And, are the people who live so comfortably while another or others suffer truly happy and justified in how they live?
Your thesis can propose the situation that causes such a dilemma. For instance, the lives of many wealthy people are comfortable because others provide the product that keeps them wealthy. But, the wealthy are unconcerned about the conditions under which these people work; they simply enjoy the comfort.