S!
MikkOwl, the difference between modern airframes and WW2 is of course quite big. The planes of WW2 were designed for less than 1000h service, like Bf109 was for about 400h and it's engine for about 120h before complete overhaul. Now the modern planes are designed for 6000h and civilian planes can fly twice or even more that amount, as their airframes are not stressed like fighters.
Materials and manufacturing techniques have evolved of course too, but for their time for example F4U was very solid build, especially the midsection where the wing was. Like a tank. Bf109 was of lighter build, but it was designed for something else than F4U for example. FW190 was a sturdy plane, but had more roles than Bf109 and of curse design philosophy was different a bit.
Have to take in account the design specs in planes because that determines quite a bit of their structure etc. But there is one commong thing for them all: to save weight where possible. Even today this is an issue so we have new materials like composite etc.
As of the performances of planes in IL-2. The debate has gone on forever, since release
Bt a serious look could be taken in the fuel consumption and fuel quantities planes have, the overheating and engine damage exploits plugged and so on. One of the most accurate planes in fuel consumption is actually the Bf109. You can fly with internal fuel 407 litres roughly one hour if cruising, but the flying time reduces quite a bit in combat. But there are planes that fly longer with same fuel capacity. This makes fighting in Bf109 a challenge as you have almost always to take 100% fuel load and then you are fighting planes that fly with 25% or at most 50% fuel because they simply use less juice. Go figure the rest.
TD is making good fixes and additions for IL-2 and hopefully continue on that path. But I wish there would be a balance between bringing in a lot of new stuff and features when some of the old is still broken. Of course all can not be fixed or is not even feasible, but basic stuff like fuel quantities, fuel consumption etc. maybe are not that hard to check and fix.