In the bonus portion of the Glyndebourne DVD of Poppea, so and so talks about the first production of Poppea directed by Raymond Leppard. His orchestration is pretty out of current taste when dealing with this period of rep, but at the time, it was fresh, new, and because it was only the very beginning of the historically informed performance movement, it was a miracle at all it was put on.
But, there is this hangover of making certain decisions: if so and so were alive today, he (because women composers aside from Strozzi?) would have looooooved the piano/modern horns/non-gut strings that don't go out of tune at the drop of a hat/etc.
The problem is -- why stop there? I had a lesson with Katherine sensei who said (and she was addressing this to deleterious vocal practices [in her view] at the altar of HIP performances) that Beethoven would have picked a piano over a pianoforte. But I also bet he would have loved the shit out of an electric guitar. Mozart too. Like, saxophone concerti, hellllooo! And Bach? He's totally be all over this theremin and ondes martenot stuff.
Ok ok, so the issue is that there are no real ancient counterparts for all this stuff, so it's not like you can perform the Goldberg Variations on electric guitars and call that equivalent to playing it on a piano. It is, after all, written for a keyboard. (Most annoyingly, modern audiences still have gender hangups with respect to baroque operas where gender performance was more fluid -- any sort of modern benefit of having a Baritone Cesare is outweighed by the violence done to registral/timbral choices of the composer)
But here's the thing -- I bet you that almost every composer would have loved the bejeezus out of amplification. And that's a dirty word to classically-trained vocalists now. But for every argument that people make about so and so loving the piano over the harpsichord or pianoforte -- I can point to cultural reactions to the Mannheim Rocket and 17th and 18th century practice of writing for and employing on the opera stage brilliant performers with incomplete vocal techniques.
Nancy Storace, the various Venetian singers at the birth of opera, Schikaneder, the list is much longer. Modern amplification of voices would allow these works to be performed for larger audiences. Composers could pick compelling stage performers who haven't the dynamic range naturally or via training to project throughout a huge space. But somehow this is super-anathema to the modern classical music community. And I'm pretty convinced composers revered in the classical canon would have gone for it.
So.....is classical music filled with super stuffy people? Probably. Should those making adjustments to works of dead composers invoking what said composers would have done if they were alive be more careful about their justifications? Undoubtedly. Could we stand to redefine classical music in a way that doesn't come across as bizarre neo-ludditeness? YES. I want to do this.