> I don't feel like these subtleties translate to MIDI

But wouldn't they be reproduced when replaying the MIDI data physically on a piano?

Ultimately isn't how you hit the key and bounce/stay still just initial velocity and then timing of letting go? Perhaps the velocity of letting go would have to be added as well, but I'm not actually sure if that's really acoustically meaningful.

I guess I don't see why all the reverb and ultimate sound complexity wouldn't be recreated in playback? Of course, this requires actual physical playback on a similar enough model of piano, or else a synthesizer that is sufficiently accurate.