I like the ideas here so far - but I honestly reckon that its time for a serious rework of the whole strat set up - you should make the whole battlefield situation more fluid & interdependent. It is time to drop the simplistic model & use a bit more complicated maths with more interdependence - and a lot more tagets.
ie instead of you bomb HQ therefore there's no dar at all, how about: local dar works - but only at close range, and bar dar shows only for the sectors round your launch/current field.
We should have some real cities - those big cities with factories & power plants & HQs & docks in them. The ack is heavier, the right target is harder to find, the buffer cares a lot less which is the right target if it means hanging around in the ack longer. We should have different factories: aircraft factories, GV factories, food factories, train factories, truck factories.
You kill an aircraft factory: aircraft are harder to replace, so less are available of the planes that are getting killed - if your country has 100 spits and 10 hurris up, and only 25% get back - you need to replace 75 spits, but only 7 hurris - which is in shorter supply? (Sure, I reckon we should factor in a demand thing too - if 75% of the country fly spits, then output would concentrate on spits more & a stockpile (to build up supplies) - the stockpile can be affected by bombing hangars & capturing fields - more fields more stockpile, less fields less stockpile & capturing the nmes field with hangars intact = transfer the stockpile you took)
You kill a power station: power in that district should be affected - factories are less productive - so rebuild will take longer, less fast replacement of aircraft, less supplies of ammo, dar affected a bit maybe? Some of these effects are immediate, some take a while to be felt.
And to top off the dumb ideas of the day

:
We should use perk points a lot more to regulate the availability of aircraft & GVs. ie - your aircraft factories are all in flames - add a perk or 2 to the most popular (as determined by the current numbers in your country) planes.
Or perhaps a quota system - first 50 n1ks are free, the rest are perked. You lose a "free" n1k, then it gets replaced at a rate of one every 3 mins - so for the next 3 mins 49 are free. You lose a fighter factory, the "free" n1ks only get replaced at a rate of one every 5 mins. You lose a power supply or a supply depot as well, it goes up to 6 mins. No perk points left? Go fly an unpopular plane, it'll be free (Hurry while stocks last!

). Perk points can be adjusted so they're easier to get, so it's less of a pain for newbies (or mebbe newbies get a set number of points to spend).
The more factors you add, the more complex it gets, but hopefully, the more complex you get the more realistic it gets. And the maths can probably stay simple enough to be doable (hey, I'm no expert), while producing a load of interesting nuances. Basically I'd want the whole Strat thing to be in 32-bit Grey, not black & white.