This will make the overall pushback procedure a bit more convoluted and longer with no actual benefit (none of those additions would have any relationship with something that affects the simulation), when most users wanted to make it a bit faster, if possible.
And, there's the added complication that, any change to the wording, would require updating ALL voices, for all accents, in male and female variations. While this might not as big of a problem for the text-to-speech voices, it is for the real voices we either hired a professional voice actor for, or for the ones that has been graciously contributed by users around the world.
If we'll ever touch the pushback procedure, it will be to do something substantial that would affect the simulation, for example the ability to pull back to the gate, in case of an engine failure. THEN it would make sense to do the effort of changing the voices as well.
