twocats Edit: to make it clear, Graham Fitch and I are talking about musical intent. Not about whether scientifically if you play with the exact same dynamic etc whether anyone can tell the difference.
@twocats I now almost regret bringing up this topic again. Can I assure you that in my mind this is not about who is right or who is wrong. Rather, it's about understanding what's really happening when a music intent and execution does or does not produce an effect. I can only speak for myself, but I'd like to believe everyone involved in this discussion carries the same attitude, too.
So, does the underlying mechanism (and science) matter, if the pianist did something with intention, and the effect come out as expected? Maybe no, maybe yes. There are undoubted many many talented pianists who don't know a thing about piano action, yet they figured out how to make great music out of it. But, I believe understanding the mechanism and science does have the potential to give less talented pianist help, or even advantage.
My knowledge of piano playing is still laughably so little. I am better at my other hobby, auto racing. Data collection and analysis has elucidated many "why such technique works", and dispelled some myths that don't work or don't work as drivers imagined. And, studying data, understanding the mechanism has proven to be the most efficient way to improve most drivers performance.
Coming back on topic of the touch, tone, and held pedal. Although I don't hear the difference, I also do not doubt you hear it. But I want to know what exactly is causing the difference. Is it really the finger motion of staccato producing a different tone of sound (when pedal was down) the that of the finger motion of legato? Or is it just because when one plays staccato finger it just instinctively strike the key a tiny bit louder? But even if it's the latter (a little louder), the effect matches intent, why does the how matter? In my mind it matters because if the tone difference is indeed due to louder, then there could be other ways of finger motion that achieves the same. Can you play legato finger but just a little louder and end up getting the same effect as staccato? If so, then you now have two different ways to make the same result - would that be handy for certain situations?
Maybe to put it another way. Piano playing, and to a larger extent art, is very empirical. One learn through enormous amount of trial and error to build up a knowledge base of what action produces what effect. Science and engineering, on the other hand, can be extrapolatory because of the focus to find out the underlying mechanism and the logic behind it. The advantage then is one can predict something to work as expected even before first try. I have personally seen the combination of the two in racing and they do work beautifully.