I am not interested in the 'mainstream' or in what 'everybody else is doing'.
I am interested in new Music notation and new keyboard instruments (alternative and improvements of the piano: J. Trotter, T. Dreschke, P. Jankó, etc.).
I know very little about accordions. Kravtsov seems to be doing something interesting, at least it is different.
Of course "best match" is not just hollow word, otherwise piano would not have been divided into black and white keys.
The white keys are simply a "best much" to a natural major/minor scale and modes. Also "accidentals" denote certain deviations from that reference "match" scale.
Is it necessary... I think it is not. People do not compose strictly diatonic music (in some genres, maybe yes, but that is subjective preference of style).
I do not know what you mean by Western music, but certainly there is "western" music with "accidentals".