While consuming “Billy Joel: The Definitive Biography”, I came across a very interesting comment by him about keyboards (Joel is a pianist). He says:

the insurgent energy of rock [music] was well represented by guys pounding at keyboards. After all, it’s a percussion instrument - you strike the keys, literally pounding the instrument. It was meant to be played hard, like the drums.

This is as relevant when referring to mechanical keyboards. One does pound them after all. Hard. And the clicky keys make a wonderful, almost musical percussion sound.