One problem with opening the upper echelons to lower classes, is that the lower classes are more desperate for money and thus more easily corrupted. You couldn't offer GW Bush much that he didn't already have as a result of his family's status, but you might have more luck with the son of a poor steel worker like Rod Blagojevich.

There are many things that had changed in the last 60 years. Trying to tell that the reason behind those changes was differences in power elite is quite shallow and not correct at all.

Link to a related post analysing meritocracy : http://news.ycombinator.com/item?id=1103408