One of the things that has always bothered me about Rawlsian liberalism is its emphasis on consensus. The Rawlsians want a state which ‘all reasonable people can accept’ or which ‘no reasonable person can reject’. To accomplish this consensus, Rawlsians have to hollow out the good until it contains only uncontroversial values. Controversial principles are not, by definition, accepted by all reasonable people. The Rawlsians therefore have a tendency to depoliticise the controversial. This results in a political theory which is committed to conflict avoidance. Families that avoid conflict tend to have conflict blow up in their faces, and the same is true for states.
But beyond this, Rawlsian liberalism produces a state which is based on lowest common denominators. This is where Plato comes in.