Let me just add a few thoughts to what you have put out there. A few years ago – recently – a well respected college professor in the area told me emphatically that when scoring any arrangement, every instrument should be set to piano “so you could hear all the notes.” He was speaking from a long history with Finale, but that attitude might have come from a person working on any platform. Indeed, in 2000, I probably worked that way for the same reasons.
I wasn’t interested in a debate, but the fact is we have come a long way from that point. I have produced a few things on the DAW that fooled some people into thinking it was a human performance, but few people will be fooled by a rendering coming directly from Dorico, or any other notation program, even using NotePerformer. I suppose most people would say that should not be the ultimate objective for any notation program. But I suggest it actually should be one of the measurements of success long-term for all the reasons you mentioned.
Auditioning music (or better yet, evolving music iteratively) is most effective when it sounds realistic. And honestly, we aren’t that far off already. Going back to that professor’s advice, if one does simple things like panning the instruments across the stereo field and maybe using a touch of compression to bring out the inner voices, one really can hear the music pretty well. And with NP in particular, the interpretation of slurs and simple articulations is good enough that it often motivates me to add markings to the score. That is to say, the same markings that make NP sound more human-like also will help the human play the music as intended. Dynamics are a bit spooky, but there have been many times that the interpretation of dynamics has been realistic enough to cause me to change the score in a constructive way.
And while most of the virtual instruments don’t really sound like the “real thing”, they do have most of the lower overtones such that you can actually hear how successful different voicings are likely to be when played by humans.
What’ I’m trying to say is that I agree with what you wrote, but just wanted to point out how far the technology has come already.