Thank you! :)
I hope you'll forgive me for adding just one more thought about this before I shut up about it. :) Given the shape of the normal distribution (Gaussian distribution, bell-curve), one would expect that there would be more beginner- and intermediate-skilled customers for the VSL virtual pianos than experts. So perhaps there's a large population of folks experimenting with a soft touch, in order to train themselves to do that expertly.
Let's imagine that the student (using a Kawai VPC-1 with the Vienna Symphonic Library Bösendorfer 280VC) puts the arm's weight on finger 1, and uses that stability to play very quietly with finger 2. As the key hits bottom, the arm's weight transfers quickly over to finger 2, which now acts as the point of stability so that finger 3 can play whisper-quiet. And so on. The student walks their arm weight back and forth from finger to finger. Making beautiful little sounds. And does that for a long time.
Then they realize, oh crap. What a waste of time! I just trained myself to play silently. Because what I was actually hearing was the sound of VSL receiving an absurdly low MIDI velocity, but playing a nice quiet sound anyway. And I know this for sure, because if I switch over to Pianoteq and repeat the experiment I hear nothing for more than half the keystrokes.
That happened to me. I had VSL starting up as the PC boots, I was so thrilled by it. Until that happened. Now I have Pianoteq as my startup piano. I'll wait a year or two until I've mastered quiet playing before I trust this software again. If it were me, I wouldn't care how many customers ask for this feature, I'd implement it as a matter of personal pride so that I knew I were developing a meaningful virtual instrument. Here's a survey of the virtual pianos I own.
True virtual pianos (these do have silent key): Garritan Abbey Road Studios CFX Concert Grand, Modartt Pianoteq 7, Native Instruments The Grandeur, VI Labs Ravenscroft 275.
Quasi virtual pianos (these don't have silent key; so they're ok to use after you're done learning and practicing, but IMHO you should avoid them for learning or practicing with): Ableton Live Grand Piano Pack, Waves Grand Rhapsody Piano, Vienna Symphonic Library Bösendorfer 280VC.
-Steve