Observe that no manufacturer in the Old Days (to my knowledge) ever
offered an electrically-pumped player piano without automatic expression
capabilities.

The philosophy seems clearly to have been that no one in his right mind
would want to listen to piano music played without expression (a sensible
outlook, it seems to me).

I think that the preponderance of treadle-powered instruments has more
to do with the enjoyment imparting one's own expression to the music
affords, than economic considerations.  Some are not aware that these
instruments were not regarded or manufactured as toys, before the 1950's.
They were built for serious musical purposes, as the craftsmanship in
them clearly shows.

Treadling seems to have been taken even more seriously in England,
where many more full reproducing pianos with foot pumps, seem to have
been made.

Larry Broadmoore