We love to play the music of Johann Sebastian Bach on the piano. It's some of the most beloved of all the piano repertoire. However, modern pianos didn’t exist when he wrote this music. Most of it was written with the harpsichord in mind. Toward the end of his life Bach knew some pianos, but these early instruments were nothing like the modern piano.
So what are we to do? There are many legitimate approaches. Some people do everything they can to try and imitate a harpsichord when playing Bach on the piano, they don’t use the sustain pedal, since the harpsichord doesn’t have one. Other people just treat this music like romantic nineteenth-century piano music and use all of the expressive tools available to the modern pianist.
I like to try and combine both of these approaches. The harpsichord doesn’t have dynamic changes in the notes. It is impossible to get louder and softer through touch. When I play Bach on the piano I really want to take advantage of the expressive volume changes that the piano affords.
I also use the sustain pedal quite liberally in the music of Bach. This is because the harpsichord is actually a very resonant and reverberant instrument, and although the harpsichord does not have a sustain pedal, to my ears the piano sounds more like a harpsichord when we actually use the sustain pedal.
There is no correct answer to this issue. Had Bach had a modern piano at his disposal he would have written different music. We are privileged to get to bring this wonderful music to life, and its up to us to find the way that works best for us.