I think it is the opposite really. Materialistic thinking is the baseline in modern society and in many ways the tendency to dismiss the unquantifiable as non-existent is one of the greatest weaknesses of modernity. It is certainly far easier to quantify the average temperature in a region using Antarctic or Greenland ice core data and use that to determine how that may affect agricultural production in a historic time period or analyze average skeleton height sizes to assess quality of life metrics than to analyze how cultural changes affected problems.

>At the root of this exists a fallacy of composition where the argument is that if each individual is virtuous, then the whole[system] is virtuous

The Romans may not have worded it correctly but it should not be surprising if we replace the word 'virtue' with 'social norms' and re-analyze how changes in social norms can affect social trust, how institutions are structured and even how families are structured(e.g. a change in norms from the religious change from paganism to Christianity meant a change from the city focused philanthropy of euergetism to the poor/sick focused ecclesiastical charity).

Social trust, for example, is very important as it greatly reduces transaction costs yet and its core much of it relies upon the concept of common shared knowledge (in the form of traditions, values and principles) that is difficult to quantify. Yet at its core, the change in social norms would be deeply related to changes in 'virtues' as virtues, in practice, are ideals that society pressures individuals to follow. So, the Romans may not have the scholarly data on material changes in the environment to be sure but they also have a better intuitive understanding of the importance of virtues than their modern successors.

Yes, and a people system has serious vulnerabilities. Consider marketing, or the impact of a handful of vaccine misinformation bloggers had on a huge segment of the population.

or:

>“. . .it’s the leaders of the country who determine the policy, and it’s always a simple matter to drag the people along whether it’s a democracy, a fascist dictatorship, or a parliament, or a communist dictatorship. Voice or no voice, the people can always be brought to the bidding of the leaders. That is easy. All you have to do is tell them they are being attacked, and denounce the pacifists for lack of patriotism, and exposing the country to greater danger.”

Those admirable qualities you mention have been not been forgotten by accident. We've been made to forget, because people without them are easier to manipulate.

It's extremely hard to prevent this, because those who perpetrate it have much to gain directly, while those who prevent it do not. Consider any environmental protection law that is costly to a business - if you benefit financially you can put resources/lobbyists/marketing against it, than the volunteers who seek to protect it can. For strictly economic reasons, in the long run, the people lose.

You can't really rely on "people". The vulnerabilities need to be patched.