It's true that the predecessor of the modern piano existed during Bach's time (and that Bach helped to sell a few). But I would argue that it was more of a cur

It's true that the predecessor of the modern piano existed during Bach's time (and that Bach helped to sell a few). But I would argue that it was more of a curiosity at the time. It certainly was nowhere as widespread as the harpsichord or clavichord. At any rate the pianoforte of Bach's day sounded very different from the modern piano, so playing Bach on a modern piano is still an anachronism. (Whether that's a problem is a separate issue.)