Sidokar You brought up another interesting aspect that I happened to be pondering over recently as well. It originated from questions in PW about limitations of MIDI 1.0's 127 level of dynamics, and whether apply a velocity curve would the worsen the resolution enough to become a valid concern. The topic interested me enough to go to my digital piano and mapped out MIDI range for each dynamics marking:
Dynamics: MIDI range
- ppp: 1-13 (13 steps)
- pp: 14-32 (19 steps)
- p: 33-52 (20 steps)
- mp: 53-72 (20 steps)
- mf: 73-91 (19 steps)
- f: 92-110 (19 steps)
- ff: 111-122 (12 steps)
- fff: 123-127 (5 steps)
At first, my reactions is just like what you said. There is no way for me to accurately and reliably produce the 20 steps in mezzopiano range! If a maestro can do that, I am in awe! In any case, 20 or so gradations for each dynamics marking seems more than adequate. And I might agree with you even 10 is enough, so applying a velocity curve should be of no concern.
Then, I put more thought into this, and realized it's more complicated than that. Take an example that I personally noticed - it is much harder for me to get the very first note of a piece played at a desired dynamics than any of the subsequent notes. And it makes sense because the first note has no reference, but the notes following have. So even when I have no hope to ensure my first note come out at MIDI value 60, I could imagine with practice one day I can make a crescendo from there within ±2 (e.g. 61-63-64-65-67...) because the ear and the muscle are just better at executing increments than absolutes.
Relate this back to my original revelation that tone quality is affected by context, then the need of precise control of the relative velocity of a cluster of notes would make high resolution of MIDI value of great importance.