Where flak batteries a major cost? Yep. In September '43, about a million people (many of them kids and women, though) were mannintg German AA defences, which used 8,876 of the superb “88” anti-tank/ant-aircraft guns, and 24,500 light AA guns and 7,000 searchlights.
Of course, the economic loss on the Allies in using many of their best men and most high-tech weapons to bomb German houses and fields (accuracy was terrible, factories extremely hard to destroy) was arguably higher than the cost to teh Germans, but there WAS a cost to the Axis.
By the way, if we’re searching for realism, allowing bombers to carry paratroops is extremely UN-realistic. Some obsolete bombers were used for paras when there was nothing else, but rarely; and I don’t think useful bombers ever carried paras.