arc But why should they also change the volume of the hammer noise? In an acoustic, the release velocity only impacts the damper and the action of that key, not the overall hammer movement, including how the hammer returns to its rest position.

Well, actually in an acoustic grand the key release has a (small) impact on the noise the hammer makes when returning to its rest position from either the checked position or from its escapement position. If you want to be totally realistic the digital piano should also take into account which ones of these two positions the hammer was before releasing, hence if the previous note was loud (checked) or soft (escapement). In my opinion this is too hard to implement right compared to the provided enhanced realism. So I agree that the main thing to take into account is the way the sound is dampened.

arc As @CyberGene pointed out, some implementations, notably Yamaha's, represent the key release not as a single event but as multiple events. This better simulates the key damper mechanism of the acoustic instrument

Yes, in fact in theory the damper might not damp completely, and then be raised again creating a number of effects. Not sure how common this is done by competent pianist, but I can attest that it is besides the capabilities of the average pianist, also because the average piano is seldom well regulated in this regard, as the Reblitz books points out. The first sentence of said book, when describing the regulation procedure for the dampers is "You are about to enter the most tedious and long process of regulating a piano" (quoting for memory, likely a paraphrase).

arc ave a listen at András Schiff playing the WTC at the BBC Proms 2018 for several examples.

There is a very long, edited (pitch shifted) and unofficial and monetized version on

Or the "official" page has only a 2 minute excerpt as far as I can tell.

https://www.bbc.co.uk/events/e92fbp

@arc If you could point out one particular example from either recording, that would be very appreciated