As social commentary, Fitzgerald draws a sharp distinction between the East and the West. The East is associated with excess, irresponsibility, immorality, and amorality. He develops an additional distinction among social classes in the East. Tom Buchanan, as a member of the wealthy Eastern establishment, embodies the characteristics of that most privileged social class, and in his scathing characterization of Tom, Fitzgerald makes a strong critical statement about the social class he represents.
Born to enormous wealth and a family name, Tom Buchanan has attended the right schools, moved in the right circles, and developed the arrogance and sense of entitlement that accounts for his moral bankruptcy. Tom is an ignorant snob who bullies his way through life, secure in his superiority and contemptuous of anyone who is not in his social class. Generations of family wealth have corrupted his character and his soul. Fitzgerald's description of Tom and Daisy make his condemnation of their privileged social class quite clear:
They were careless people, Tom and Daisy--they smashed up things and creatures and then retreated back into their money or their vast carelessness or whatever it was that kept them together, and let other people clean up the mess they had made . . . .
Tom Buchanan is important in the novel in developing Fitzgerald's social commentary because he represents an essential element in the corruption of the once great American Dream. Generations of inherited wealth have weakened the moral fabric of the country and undercut the principles and values upon which it was founded.