As a kid I always wondered why there was a missing key between Fa and Mi in piano keyboards. Later I learned the reason. There is only a semi-tone distance between this two notes and therefor no in between note for the piano.
Although this explains the reason of the missing black key it does not explain why keyboards where setup like that initially. I assume this already comes from the organ, and probably even from previous key instruments that kept a familiar setup to make it easy for already existing keyboard players to learn the new instrument, but how did it all start?
Nowadays one can argue that the keyboard reflects the Do scale, a very popular scale, but through history this was not always the case.
In my understanding, for the first instrument builders, it would make more sense to just make a continuous keyboard, with the chromatic scale, where Mi would be white, Fa black, and next to it, in the sequence, a white Fa sharp... etc.
Why do keyboards have the current configuration based on the Do scale?