Love that answer.
Some composers undoubtedly would compromise I agree.
It depends on how much perhaps.
Is a 30% change in tempo an adjustment, I ask because Grieg did play 30% faster in tempo than many recent recordings.
We often speak of 1% 2% maybe 5% but 30% is a huge change.
Imagine an orchestra about to play the 1812 overture which takes 15 minutes normally, being told by the event organiser "Thats great but I need you to finish it in 10 minutes or less."
I can imagine the 1812 played in totality in 9 or10 minutes but that is neither an adjustment nor is it a palatable concept.
I think chaos is an apt description.
Pace is critically important if the pace is too fast emotion and meaning dies. Equally if the pace is too slow understanding and meaning dies.
And I dont think Samuel Barber would have agreed to knocking out his Adagio for Strings in 5 minutes instead of the 8 it usually takes.
The feeling and sense of a work is bound up in the pace and to knock out a contemplative work at 100 miles an hour does nobody any favours least of all the composer.
Likening this to Fine Art Picasso painted Guernica and the canvas is 11 feet 6 inches. If a gallery approached him and said " We love the work but we only have a 7 foot long space for it, can you shrink it down to fit our 7 feet long wall", Picasso I am sure would have replied " No, get a bigger wall"
You ask does it matter musically if the tempo is altered, great question. I think it does, if the composer wanted it substantially slower he would maybe have composed it that way, does it really matter if we slow it down slower and slower until an energetic work sounds lethargic and sluggish if we choose to.
The flight of the bumble bee was composed at 178 BPM and if audiences want it performed at 30 BPM should we perform it at that pace. I think not, it is a 178 BPM piece its majesty energy and power is a result of its pace so that is how we should play it.
I suggest that this question is already answered by the people who have ridiculed the modern Baroque orchestra musicians who played the work at the fast pace they believed it should be played at.
If the tempo of the work were unimportant then those who complained would not have made an issue of it.
I am however on your side to an extent in that I believe it is good to play around with tempo and reach for a new perspective but this ceases to have meaning if we are unaware of the tempo the work was originally composed at.
It is all relative after all.
But there is a limit if we slow the tempo enough we eventually reach Larghissimo at 24 BPM, and then music ceases to be notes separated by spaces and becomes spaces separated by notes, it then becomes meaningless and then we have destroyed the music.
So I guess it is important.