I've always supported manual calibration in the MA's.
Honestly, what I think would improve the bomber game, and the whole "war" thing in general is, in no particular order:
1) manual calibration
2) max limit on resupply of strats (say, like 60% max, at which point it has to self-repair)
3) more limitations imposed on 163's. That being fewer bases (like, maybe 2), with those being further from the strats and HQ to end last-minute defenders, and an increased perk cost.
4) more realistic auto puffy, with an actuall shell being launched from the gun, with a historically correct flight time and accuracy. Target location, speed, and vector would be updated every 3 seconds, as opposed to instantaneously.
This would make evasive manuvers far more effective, but conversely the final approach much more dangerous.
5) AAA would concentrate on bombers above fighters, not the first to enter the FlaK belt (so as to prevent a fighter from coming in first, and drawing/distracting most of the flack).
6) increased impact of strats on the war. If fuel is dropped to zero, fuel is limited to 25% regardless of field size, location, and aircraft used. Facilities must be repaired to 50% before 50% fuel becomes available, to 75% before 75% fuel becomes available, to 90% before 100% fuel is available, and to 100% before DT's are available.
For ammo (depending on aircraft's options), it would either restrict the carrying of external ordnance and gunpods, or force the selection of a lighter ammunition/gun load (at 0%, a P-47 would have to fly with the 6-gun option with the lightest ammunition load, no external ordnance. A P-51 would take the 4-gun option with lightest ammo, a C.202 would only be able to take the 12.7's. C.205 would be able to take either, as 4 weapons are always carried. 109G-14 could still mount the 30mm, but not the 200rd 20mm option)
For radar, bases would have radar repaired based on their proximity to the strat/supply depot (see next item). At 50%, the 1/2 of affected bases closest to the relevent depot/strat have radar repaired.
7) tiered strat system: Main Strats (affects entire country)
which supplys Theater Ordnance Center (affects the half of the bases origionally owned, line clean down the middle when possible, Theater beaing Knight Theater of Operations, or Bishop Theater of Operations
Theater center supplys the Army Group Depot, which is divided into, for example, North, South, and Center on a large map, or would be East and West on a small map (either a 1/3rd or 1/2 split of the Theater bases).
AG depot suppys Army Central Depot (responsible for 1/2 the bases of eacy Army Group).
And if the map is large enough, we could include Corps-level depots, which would supply 1/2 of the Army's bases. Effects and rules of hitting a supply depot are the same as those of the central strats, but just affect a smaller area.
The more time and planning you invest in hitting the targets, the larger impact you will have. Defense of a base will become near impossible if strats are completely knocked out