The reason greed has been ignored is that it lacks explanatory power. No one has established the mechanism by which greed varies over time, therefore affecting prices. Firms having greater pricing power - and reaping the benefits of that via higher profit margins - does not prove that greed has increased.
Capitalists are greedy is a basically accurate but also obvious observation that doesn't really teach us anything about the world.
Capitalists are greedy is a basically accurate but also obvious observation that doesn't really teach us anything about the world.