I think that for many, including myself..the 2 worst parts of this (unit withdraw) are:
1: That they pull from the front to fill up, then leave..though I actually can see the logic in the reason above(doesn't mean that I like it or even agree, but I can see the logic).
2: That it comes regardless of current game conditions..and while I understand the logic here, as well.. I disagree with it still. If you are leading your pixeltruppen to glorious victory after glorious victory, the Red Army is running away, and all is beautiful in your little Axis world...it still seems arbitrary to see that somehow in the West, it is not going so well, and you need to pull units from the East to fix.. In the real world, the Wehrmacht as I posted in another thread some weeks ago...devoted 60+% of their entire war effort to the East Front, where they saw their "real enemies" If the Soviets were indeed crumbling, it is quite likely that the Western allies would never have even attempted their landings, or, if they did so, the timing for them would have been much delayed as the British, in particular, had a very specific set of prerequisites which they needed to achieve before they attempted, at least, the "big one" in Normandy.
Having said that, I also think that with only one front in the game, I can understand 2x3's reason for this design choice..it definitely makes me more anxious to try an eventual "War in Europe" where we can make the decisions for both fronts however. Then again, perhaps that is their secret plan after all...lol