Predictive power has not always trumped understanding as a goal. The original Copernican theory did not work as well as the Ptolemaic model used by astronomers. The Ptolemaic model as it had evolved in the 16th century was extremely complex with many fit parameters and predicted planetary motions relatively well.
All of the models shared the incorrect assumption of uniform circular motion and epicycles, both the Copernican, Tyco Brahe's hybrid system, and the traditional Ptolemaic model which by virtue of the thousands of years of effort invested in it -- it arguably dates back to ancient Sumeria -- actually predicted the motions of Mars and other planets best.
It was only the addition of elliptical orbits with non-uniform motion by Kepler that resulted in the new model surpassing the Ptolemaic model.
In the case of planetary motions, understanding ultimately proved critical. We can predict planetary motions to about 1 in 100,000 accuracy versus about 1 in 100 with the Ptolemaic model of the 16th century.
I don't think it's about low-hanging fruit so much as the difference between analytical understanding/talent and deep creative insight.
Science-as-career has become institutionalised and conservative, and slanted more towards the semi-industrialised production of regular publishable refinements and less towards deep insights.
It's correspondingly less likely that a mind like Einstein's would be able to make equivalent contributions today.
I'd just point that, even tough Schrodinger and de Broglie were pretty much focused on understanding, their contribution to quantum theory was very prediction-based, and not so much understanding based. As I said up there, it's not that they believed that, it is that they only got results when working this way. I took Einstein away from your list, there are always exceptions.
What I think is most interesting is that the XX century got an example of each of those "ways of doing science" working. There was probably a "right tool for the job" effect there, as people certainly weren't trying to create a predictive-only theory.
In particular the "losers" at the 1927 Solvay Congress -- Schrodinger, Einstein, and de Broglie -- seem to be the antithesis of "shut up and calculate" and all contributed very critical elements of quantum theory.
Schrodinger found the Schrodinger equation, the differential equation that describes so much correctly, through his approach. This is significant because the operator methodology of Heisenberg and Gottingen either did not work, despite the claims it is equivalent to the Schrodinger equation, or was essentially impossible to use to make predictive calculations. Schrodinger's publication of the Schrodinger equation provided an easy way to calculate results in QM that proved correct using well-know differential equations/calculus methods.
For whatever reason, perhaps to keep their research program afloat, the "winners" at the Solvay Congress jettisoned the conceptual underpinnings of Schrodinger's approach and married it to the operator formalism leading to quantum field theory with its intractable infinities and other problems that remain to this day.