This is not about balance but realism.
If you want talk about balance go to some arcade game where climb with your Corsair like a rocket and shot with his eight cannons or to some Call of Duty or Battlefield forum where you can degree shotguns, MGs and pistols to rush with your Thompson like gun at will.
This is about realism, this is about make the most realist WWII airplane behavior out of real documented data and real pilots to make the most realist
Simulator.
Its not the 1940s airplane engineers fault don't make Hollywood planes like.
If a plane have weak points is in the hands of the pilot get over it, in fact every plane have weak points, if your plane is weak at speed you should rely in maneuverability, if your plane is weak at climb you just should stay at low altitude.
This is not about balance but Realism.
This is IL-2 !!