This thread seems to be planing on different levels. MIdi can of course be 'programmed' with those notes but what GeneP (and me for that matter) is saying I believe, is that it would not represent nearly enough, music of a complexity demonstrated in his post above and the expressive reach that live musicianship and ensemble imparts to such work. In fact, the vital 'music' in a midi/sample rendition would be lost imv, much to the detriment of the great classics.
However, I'd love for someone to try and match a live recording of the Strauss with the best available in samples to see how close we can get at present. Another thing, how would one for example perform with samples, the 5 violas harmonic glissando sul C in Gene's second example? Is there anything out there that could do this at the required dynamic and tempo?...I'm genuinely asking as it'd be nice to have a flexible, programmable harmonic gliss for all the 4 strings of each string instrument...oh with solo and divisi options too...
Likewise on a different plane and getting back to the OP, a composer's creative mindset can be hampered by sample limitations and they may have to decide between writing to sample strength or write in a more unlimited way on the manuscript. Writing successfully, free of sample limitations requires more knowledge than synthestration and the decision on how to proceed (synthestration or orchestration), is inevitably influenced by how much one has an understanding of individual instrumental capability and instruments in combination with others, along with the artistic intention and/or the reason for writing. One can of course, embrace the samples for what they are and with full orchestral knowledge or not, still produce artistic worth.
A mixed approach will inevitably have to be used by those fluent in synthestration
and orchestration in the absence of real performance, unless they decide
not be dictated to on the ms. It's quite the artistic trap and the temptation to give in to what sounds ok in the DAW can be a limiting factor for some.
Here's another perspective: When Strauss or Mahler or whoever was composing for orchestra a hundred or 150 years ago, the orchestra was IT. That's all they had, that's what they knew, that's what they wrote for.
What is the end game here? Sure, as musicians the end game is to write the best music we can, to put our commitment, time, energy and love into what we're making. That's a given. But isn't the goal, in a more general sense to be happy, to be a reasonably content human being, to strive for, yes, of course, but also to be able to go to work and be grateful, thankful that you're alive and lucky enough to be able to even be writing music. Any one of us could drop dead any moment, get COVID, get into a car crash, whatever. Life is uncertain in every respect. The pandemic just brings it out more.
If your chief pursuit is to take a classic, say a Mahler symphony, or a Strauss opera and interpret using samples and a DAW, well, that's certainly your right to do that. And if you do, you'll probably learn an awful lot about music, harmony, orchestration and sequencing in the process. But remember: You're re-adapting a work for one medium into another medium. Strauss and the other composers of that day knew nothing of our instruments today. They wrote for their medium. Not ours.
When it comes to writing your own music, might not the wiser course of action be to decide: Am I writing for a new medium as an end in itself, or am I settling for something I don't really love because what I really want deep in my heart of hearts is getting works played well by a great orchestra (not to mention getting a good recording)? But these opportunities are really hard to get unless you're writing for film or some other commercial pursuit, which brings an entirely different set of compromises. (The politics and economics of getting works played is a whole other discussion). Remember, composers are in a profession where we're literally competing with about 300 years of dead people! Yes, most of the music played by top American orchestras is music composed by men (very few women unfortunately) who passed away decades or centuries ago. Now that's competition!
If your dream is to get all, some, most, or even one of your serious works played by a live orchestra, go for it! Keep on pursuing it until you get what you want. But I think comparing what samples can and cannot do relative to a live orchestra is kind of self-sabotaging. Part of the problem is in the terms we use, terms like "mockup", or "symphony" (I plead guilty) or "virtual orchestra"--they invite us (tempt us) to compare what should be a new, exciting musical frontier with a long-established tradition. I personally do not think this is healthy.
To compare a live performance in a great hall with expert musicians, an eager audience, a gifted conductor with a recording of a virtual electronic piece is, to my mind, such a futile comparison that I don't ever even go there. First of all, the psycho-social aspects of live musicians interacting with each other in real time is not duplicatable with MIDI. Even when I improvise with just one or a few other musicians, I realize there's a give-and-take component of the experience that is unique. I think we're setting ourselves up for unhappiness and frustration by comparing the old way with the new way of music-making.
So how is it I wake up nearly every morning, eager, enthusiastic and excited to go into my studio and work in a medium that will never be a real orchestra? Because I never pretended, even to myself, especially to myself, that it is that in the first place. I completely accept it as a different way to make music. Better? Worse? Good? Bad? It doesn't matter, what matters is I show up, do my best, and let the chips fall where they may. I am not seeking immortality through music, I seek it through being human. If I put meaning into my work, and I get meaning out of it, that's all that matters to me. I could be dead tomorrow and I sure as hell don't want to spend my life not appreciating what I do have and what I can do.
Mike's work is incredible. I keep urging him to post on here but he has his own reasons for not doing so and I respect that. I know he's worked with top players for years, which I am sure colors his thinking on these matters. And yet I've been listening to his MIDI interpretations of his scores and they are, by any standard, superb. Are there some moments where we might realize we're hearing samples? Sure, but so what? He' still showing great skill as a composer, orchestrator and electronic music producer and I think the hair-splitting he does regarding samples vs real players is beside the point. If you're really a good composer and you know you are, why do you care if some one picks apart your work and exclaims "Yikes! I heard a sampled instrument"! Maybe that person is unable to let themselves really sink into the music for reasons having nothing to do with you or your piece. Does that make you a fake? Illegitimate? Not a real musician? C'mon people, get some courage and self-esteem going and believe in your creativity. The medium is just a medium. It's not your entire destiny.
My philosophy has been and still is to embrace the medium I work in. There are people who love my work, people who hate it and people who are utterly indifferent. Should that matter? Just keep growing and learning. Life is short. A photograph isn't a painting, yet there are great photographs. A film isn't a play, yet there are great films. A recording made with samples and synthesizers is not an orchestra, but there are people do great work in this medium. What's the problem? I really don't think there is one.