Maybe it's just that the demo was probably (possibly?

) PLAYED on an 88 wood controller (although it used the T3 piano) and the touch sensitivity curve on those promotes a much higher degree of pianism?
Also, you have to ask yourself, are you the pianist that the demonstrator was?

As with most sounds, it's the way you play it, and not the sound itself that has MUCH to do with a demo's realism...