The argument that it is not realistic in AxA doesn’t make much sense. If it were more realistic, it would be cumbersome and ineffective if for no other reason than the completely unrealistic number of interceptors that the defender can build (esp. since B29 could not practically intercepted or hit by AAA at all) compared to how difficult it is to bring along escorting fighters in most circumstances.
Strategic Bombing by the USAAF/UK Bomber Command would probably not have been successful at all, had Goering/Hitler not been a pair complete idiots and wasted the entire potential of the force on disparate, random objectives and attrition.
If the FW190/Me262 projects had been functionally deployed instead of wasting massive resources on ground based guns, rockets, and developing nearly 50 types of aircraft that were never even produced, pretty much all daylight bombing (or all bombing, with enemy radar equipped night fighters) would have not been worth the risk to the bombers or the reward in terms of production capability diminished. If Germany had formulated any plan to secure a fuel supply, what they did produce would not have been grounded and ineffectual.
A very obvious “sustainability” metric was developed early on that if the number of bombers lost on each mission exceeded the ability of that country to replace airplanes and aircrew, that such a strategic offense could not be sustained in even the medium term and would be logically indefensible and unsuccessful as a failure to concentrate forces at the point of maximum return. Fewer and fewer bombers on each mission creates diminishing returns and the Germans were able to repair most of the damage done until the number of attacks and their frequency became overwhelming.
In the end, a concerted Strategic Defense by interceptors may still not have made the difference, because of the overwhelming numbers of US bombers coming online. However, it likely would have made the offense fairly wasteful and ineffective. Just as German losses in Russia were the reason that Germany could not defend the Atlantic Wall, The German losses in the Battle of Britain and Russian Front (and their obsession with offense) meant that they had little chance of hindering the bomber campaign. This demonstrates that is the failures of Germany, not the successes or brilliance of the allies’ strategy that led to the Bomber campaigns perceived successes.
In sum, the bombers were simply too vulnerable and expensive to make the damage they did worth it, except against a feckless and unprepared adversary, which they found in Germany.
And, within 10 years of the end of the war, guided missiles put the entire concept in jeopardy, even though exponentially improved performance and damage (done by nuclear bombs) could no longer justify the use of strategic bombing at all (by 1968 or so). Perhaps if Germany had not wasted their resources on the V2 and the Fritz X and instead focused on creating the first viable airborne interception missile, the air war would have had a different outcome.
Applied to the game, SBR/Air War cannot realistically be tweaked (by changing #s, costs, or rules) because the proposed tweaks I have read tend to make SBR not worth the risks, or leave it slightly overpowered (I say this because the damage done by 2-4 bombers is all that is needed to wreck a player and im typically facing more like 8-10 of them).
The only tweak I would endorse is reducing the damage bonus from +2 to +1.