Any more than I see the need for communist societies to be dictatorships.
I believe that our society, based in capitalism can be improved. I do NOT see any need for an 'entrenched' underclass in capitalist society. For some to have more, some must have less, in a society of finite resources. I do NOT think this even implies an underclass. Now, I'm not saying that we don't HAVE an underclass in our (flawed) implementation of capitalism; we do. I'm saying that capitalism does not imply underclass, and lack of an underclass is not mutually exclusive with capitalism.
Socio-economic movement in our country is impaired, yes. It doesn't have to be that way, though.