This is one of my favorite phenomena: again in again, across various fields of study, breakthroughs in discovery allow us to go from relative ignorance to a level of knowledge and understanding that enables clear and clean conceptual models; then, as we learn even more, we realize how much more complex and weird and multifaceted reality really is.
It’s like a Dunning-Kruger effect on a field-wide scale, but in a good way. Rather than an example of hubris, it’s an opportunity for awe.
I think this can be explained by the dictum "big effects get discovered first"
It does present a weird science communication problem. After the first generation, scientists are all focused on "little effects" and don't get excited about talking about the big effects any more. They like talking about what they're working on (little effects). Textbooks drift from fundamentals and new entrants and outsiders get a distorted view of reality.