Somehow it already does. In 1942 it doesnt make sense to get the original models of Pz III or PIV, its just canon fodder. So it doesnt really matter how expensive these vehicles are.
In 1942/1943 the feature gets more interesting again. If you got only a small amount of Pz IV F/G or some early Tiger tanks its very annoying if you lose them. Later its getting boring again, doesnt really matter if you but a Panther D, A, G or even the prototype model. Like a said before, the feature needs a shared pool for some models.
Talking about infantry I never had a problem with the limited stock. I always equip my infantry with speciell heroes, so the enemy doesnt fire back, or at aleast I shoot first. You also get a lots a super heroes for infantry, so if you keep them protected in the enemies turn, you wont have much losses.