Great idea and I’m shocked this doesn’t exist.
It would likely be very, very expensive.
A compromise that is affordable and does exist is programmable response curves to key velocity and aftertouch pressure. It can make sense to have different curves for eg. piano vs harpsichord even if you can’t change the mechanical key impedance.
I haven’t seen it in the wild, but using this you could make the wrong notes quieter/louder or even play a different sound. But I think we all know when we play a wrong note, so the utility might be small.
> key velocity and aftertouch pressure.
Just a tangential note to say whenever I see these terms in discussion of MIDI keyboards it reminds me how disappointed I am the vast majority of MIDI controller (and multi-thousand dollar flagship synth) keyboards still don't fully support per note velocity or polyphonic aftertouch. It's only been 40 years kids... (sigh).
Not really needed. A synthesizer is not a piano, it's essentially a wind instrument.