I only suggested that a very narrowly issued weapon (squad leaders and up) be left up to the personnel that rate one. And generally speaking those personnel have the maturity and discretion to make an educated and sensible choice. They also get paid more than E1 through E3s.
I can categorically assure you that maturity and discretion are NOT automatically conferred with ranks E4 and above.
There is a simple, essentially FREE method that would solve issues with this or that pistol being the preferred individual weapon. The military doesn't like to do it, primarily because of the immaturity and lack of discretion making educated and sensible choices with so many of their personnel.
And that is, simply to ALLOW the individual to carry what ever they wish, in ADDITION to their issued weapon. All costs (including ammo if not the military round) to be borne by the individual.
No, its not a perfect solution but nothing can be. Smart commanders often allow significant latitude to troops "on the sharp end" that cannot be allowed in garrison conditions, as despite our respect for them our troops are, as Kipling put it, "not plaster saints". And I speak from personal experience.
because the handgun is without a doubt the least consequential weapon in a firefight.
While I cannot argue this point, there is another point to consider, one where the handgun is the MOST consequential weapon to the individual.
It is often said that handguns do not win battles, but a handgun might be the thing that saves the life of the soldier who does win the battle.
There are many stories from combat zones throughout the last century of "private" pistols (not issue weapons) saving the lives of troops, particularly in cases of enemy infiltration. One fellow I knew was the 4th owner of a Colt .38 snub that had been passed on each time its owner left the unit. He said it was a great comfort to him more than once.