This is entirely a point of speculation on my part:
Proposal: The early Scholastics focused on the ethics of economics because of the explicit metaphysical realism that sees a good economy as an ethical one.
One of the frequent points that I’ve heard about Scholastic economics is that it was concerned not with a science of economics, but with the ethics of economics. Given what I’ve read of Aquinas this seems to be false in the first supposition. One cannot have an ethics of economics without a theoretical understanding of ethics. This is the move we see from Socrates’ focus on ethics to Plato and Aristotle’s focus on metaphysics and understanding the nature of man. The ground of ethics is metaphysics and particularly the essence of man.
It seems that most modern ethical discussion of economics resolves into practical consequentialism. We must permit/forbid price gouging, because otherwise something bad will happen. There is no examination of the essence of the act itself as either just or unjust, but rather its consequences are all that matter. This stems from a nominalism that ultimately denies the reality of essences.
At the Acton Institute I’ve seen attempts to introduce discussion of virtue. However, there is too much implicit/explicit acceptance of the ethical error. Virtue comes in from the side and hopes to find a home, but it is like trying to plant seeds in salted earth. A view of economics and ethics needs to be built from the ground up and must abandon modernity’s errors, even if they’ve become economic dogma.