For that matter, I don't know of any biology classes that teach Darwin or economics classes that teach Adam Smith, except in a passing, general sort of way.
I'm sure everyone knows about Darwin's finches and Smith's reasoning about the butcher's benevolence but that's a far cry from making a detailed study.
Fields move on. Ideas are refined and re-expressed in terms not available to the originators of those fields.
These texts are all valuable as historiography but it shouldn't be surprising that students learning the material don't go to them first. More often that not they were wrong about a great many things, Smith and Darwin included.
I'm sure everyone knows about Darwin's finches and Smith's reasoning about the butcher's benevolence but that's a far cry from making a detailed study.
Fields move on. Ideas are refined and re-expressed in terms not available to the originators of those fields.
These texts are all valuable as historiography but it shouldn't be surprising that students learning the material don't go to them first. More often that not they were wrong about a great many things, Smith and Darwin included.