Malus’s law does indeed describe the amplitudes of the resulting light, but it does not say “why”, only how. In the same way that Newtonian physics assumes gravity but fails to explain its existence.
For more in depth look at this there is a 1995 paper by K Wódkiewicz contrasting the corpuscular formula with the quantum explanation IIRC.
Obviously, despite its explanatory power, we know that QM is incomplete so YMMV, but I’ll take QM over light corpuscles, until something better comes along.
Having light corpuscles that have poles and can experience fits of easy transmission/reflection is not much mathematically different from having photons with spins and wave phases, to be fair.
And Malus' original justification of his law straightforwardly carries over to the photons.
For more in depth look at this there is a 1995 paper by K Wódkiewicz contrasting the corpuscular formula with the quantum explanation IIRC.
Obviously, despite its explanatory power, we know that QM is incomplete so YMMV, but I’ll take QM over light corpuscles, until something better comes along.