Whilst I like the idea and am all for it, I think the suggestion that the current approach is less 'realistic' and more 'gamey' is quite the opposite and the proposed suggestion is more a step toward a unrealistic/gamey behaviour to address a micromanagement headache.
When troops are lost in battle, typically more troops are simply deployed from home as available or are relocated from other locations to replace the losses. I can't see them uprooting entire battalions/regiments/divisions en mass and transporting everyone home whilst more people are trained to recover from battlefield losses.... if anything that would be a even bigger logistical headache.
I agree that the game is trying to model reality here, and it feels like it does a pretty good job to me.
However, in WWII whole divisions were also brought back from the front lines from time to time, for various reasons. Heavy casualties, long tours of duty, movement to a different theatre, etc. In the book titled "The Liberators: My Life in the Soviet Army" by Viktor Suvorov, he tells the story of the invasion of Czechoslovakia in 1968. During that invasion, one particular army had a complete failure of discipline. It seems that the area they were occupying had a large schnapps distillery, and they "liberated" its contents. Even after the officers confiscated all the alcohol they could find, the men kept turning up drunk; it turns out that they had filled all the radiators of all the vehicles with alcohol, and every so often they would spend some time under a vehicle "repairing" it. Suvorov and all the men of his division (I think I recall that he commanded a battalion) were shipped across Czechoslovakia one night, without any of their tanks, to replace the men of a disgraced tank division. He assumed that they in turn had been shipped to Siberia for re-education.
On the other hand, I recall reading a book by a British man who enlisted in a regiment of tanks. At the time, the regiment was stationed in Egypt, so he had to go find it. He sailed down to Casablanca and took a train east as far as he could, then I believe he hitched a ride on a truck. At some point he caught malaria and spent a month in a hospital. He snuck out of the hospital without being discharged, and found a pilot who agreed to fly him further east. Eventually he made it to Egypt and found his regiment, who were somewhat surprised to see him. So you can see that it wouldn't be terribly unrealistic for some elements of a formation to be recruited back on the home-world, and then make their way to their formation by civilian transport. Now that I think about it, I think he might have been a lieutenant rather than an enlisted private, so maybe limit that to HQ units? On the other hand, just after he arrived at his regiment they got orders to board transports and head back to England, after which they were deployed to the continent.
