The phrase "the essential feature of" is correct and usable in written English.
You can use it to refer to one of the defining characteristics of something. For example, "The essential feature of a successful business is the ability to adapt to changing market conditions."
The essential feature of science was not its verifiability, but its falsifiability.
Torsion (twisting) of the frontals, ethmoid, and mouthparts is the essential feature of the flatfish skull.
The essential feature of the New Deal realignment was that it produced not only Democratic victories but also Democratic partisans.
You could say the essential feature of the trilogy is not what it takes from its precursors, but how thoroughly it fails to apply it.
John Gaffney, professor of politics at Aston University, says: The essential feature of Corbyn's success is not about policies but narrative and emotion.
The essential feature of all pyroxene structures is the linkage of the silicon-oxygen (SiO4) tetrahedrons by sharing two of the four corners to form continuous chains.
The essential feature of imperial worship in ancient China was the elaborate sacrifices offered by the emperor himself to heaven and earth.
The essential feature of mass transportation is that many people are carried in the same vehicle (e.g., buses) or collection of attached vehicles (trains).
It's a weird paradox that the essential feature of technology is talkativeness, but usually without the sound of human voices attached.
The essential feature of LCDs is that the pixels in them switch between amorphous and crystal-like phases, which changes their optical properties.
The essential feature of crystal field theory is that there is a competition between the magnitude of the CFSE and the pairing energy, which is the energy required to accommodate two electrons in one orbital.
