I know you spent a lot of time on this thread, but SC has already decided they will not add this feature.
This is because this feature makes the game more autonomous, where the only thing you actually do is collect some resources and wait their the builders (and of-course, placing troops on the battlefield).
It also is somewhat hard to add. To do this, SC needs to put a lot of server space aside for all the millions of troop compositions (maybe 10 million or more). This could lag the game up A LOT. This feature is also hard to streamline into the GUI because the barracks screen is already rather crowded.
In summary, SC doesn't want to spend months implementing an idea that will lag and make the game less player-based, especially since it only takes a few seconds to do the alternative.
Personally, i would be really glad if holding down on a troop increases it at regular intervals ( by 5) instead of the seemingly random numbers we get.
But sorry, this idea is ruled out.
cheers