You seem to anticipate what I am going to say with each sentence down, but in order to lay out my position I will just have to answer each sentence even though I realize you will answer it with your own thoughts in the next line down.
"The main point of the tone is as a vehicle for the text."
That is how you see it, but this is not by far an axiom. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š By seeing how Byzantine Chant developed, it seems that the authors believe the tones themselves to be as divinely inspired as the words they convey.
"Sure, the tones have different theological concepts about them, but if you want to overemphasize that point, then you might as well just jettison the text and humm or use some other vowel and just vocalize the tone/melody."
Certainly, if the text will become incomprehensible by forcing the music, then it should not be forced. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š Thankfully, given that most Byzantine music for instance is modal, this rarely happens, and 90% of Byzantine hymns can be set into English perfectly. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š As for your statement about humming, etc., I think you are stretching the point so far that your example is practically meaningless: no one is arguing that text is not important and can be dispensed with so there's no sense that one "might as well jettison it." ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š My point is only to knock down a little bit this idea I see floating around that music has to be perfectly set to the text--this just doesn't happen in the original Greek all the time and so I have to assume that it was not as clear-cut as some today would like to make it.
"Sure, there are instances were this happens like in All-night vigils, but with the main body of most services like with the Antiphons & Troparia for Liturgy or Lord I Have Cried & Apostica for Vespers, there is no good reason to not make textual and/or musical changes to ALL forms of liturgical music if warranted."
This happens in Greek Divine Liturgies often as well. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š If you are arguing that in English we should try to set melodies to the proper sentence structure, I say fine; but in the cases of automela which are the few Greek hymns that are set to meter and cannot be easily fit to other languages, I say bend the text a little and bend the music a little if by such a compromise you can still get a reasonably-normal hymn that preserves the automela as close as can be, rather than jettisoning the automela completely since it can't be perfectly fit to English texts. ÃƒÆ’Ã¢â‚¬Å¡Ãƒâ€š If you are speaking about Greek though, I would say the most obvious reason why one would not try to fix the text is that it seems to have been working fine since at least 1814 when the notation was reorganized, so any attempt at "fixing" it would just be superfluous and quite possibly be introducing a concept into Byzantine Chant that does not exist: namely that a melody MUST fit the text instead of the two fitting each other.