Gscholz is right - I sincerely agree.
There are a few reasons to suicidal mentality, and weak field defenses is just one of them only. Strengthen the field defense, and we will just see more people going into kamikaze attacks. Instead of strengthening field defenses, we should rather seek ways to weaken the effectiveness of kamikaze runs.
One solution, is to give back the dedicated ground attack planes their roles:
A single P-47D-30 carries 5000lbs of ordnance in AH(2x1000lbs + 10xHVAR(250lbs each) + 1x500lbs). A single P-51D carries 3500lbs, P-38L 4000lbs, F4U-1D 3500lbs. The Typhoon, carries 2000lbs, but is also the fastest non-perked fighter of the set.
These planes, in the hands of a good pilot, can knock down 1 major field structure(hangar), and 3~4 more minor structures.
That's not a problem since there aren't many good pilots around. But the problem is, their incredible armament option, (usually) fast speed, and potent fighter capabilities, also allows a bad pilot to take out 1 major structure, or various minor structues, before getting caught or augering to the ground.
While it is not strange to see late war planes which evolved into a multi-task fighter doing multi-task roles, in terms of planeset/gameplay, it encourages suicidal mentality and lopsided plane usage - because one or two deaths(even if not intended), will get your job done. Gather three~four people thinking the same, and you get a force of power that can shut down a small aifield in its totality,
Personally, I prefer the perk method. But whatever else method there can be out there, the point is in either limiting the usage of those late war planes, or limiting the usage of particular ordnance options, so the player behind the stick would have to pay(in one way or another) and feel the bitterness of death.
The goal we must seek, is to limit air to ground effectivity. If somehow the usage of those late war planes(at least in the attack role) can be limited, the alternative, perk-free(limit-free) A2G attack planes with decent loadouts will naturally be the less capable planes such as Mosquitos, 110s, 190F-8s, Il-2s and etc.
This serves us with some positive effects:
1) Since the perk-free(or whatever type of limit-free) A2G planes with decent loadouts are less capable, they will be easier to intercept.
2) Being easier to intercept means, they won't belike P-51Ds or Typhoons just ignoring all interceptors and going straight towards the field, shouting "Banzai!". They will get caught.
3) That means the rate of successfully achieving mission goal(whether he survives the mission or not), will ultimately be lowered.
4) To do successful attack runs, proper steps and precautions will need to be taken:
If they choose to come in with altitude to ensure penetration to target field, the interval of punitive suicidal strikes will naturally become longer(ever try taking a fully loaded Mossie to 20k?).
If they come in low, they will be easily caught before reaching the field.
To be successful in those slower, lumbering attack planes, it would actually require some skill in situational awareness - how the airpath may be open, how friendly air cover clears the skies for a needed time.
5) Since they are hardly competitive as close-range fighters, jabos such as Mossies or 110s are relatively easy prey(although there are some good pilots in those planes).
Unlike the P-38s or P-51s dropping ord, and immediately switching to CAP role with great success, the dedicated attack fighters will probably become the first of prey to fall, against normal field defenses, organized defenses, and counter attacks. This means, even if suicidal hits continuously pound a base, the remaining field CAP/vulch strengths of the attacking side is greatly weakened.
6) Since the dedicated jabos, actually carry less bomb loads than compared to the late war USAAF fighters, it will take more of them to swiftly and decisively knock out major field structures before they respawn. Unless one side has uncountable numbers advantage, when two sides (of simular force) operate in the same sector, more piloys allocated to jabo duty means weaker fighter power. A balance between fighter power and jabo power will be required, since if the late war monster planes are somehow limited, the role of planes will distinctively diverge between the fighter role and the attack role.
7) If they choose to do what they used to do - dropping ord, and if they luckily survive the attack run, switch to fighter duty - they will have to do it in the limit-less planes. Most fighters outside those normally used for jabo currently, carry a single 1000lbs, or 500lbs bomb, with maybe a couple of rockets. The P-47D-25 has to armo the bazooka pods for rocket power, and most other planes can rarely carry more than 1500~2000lbs.
In any case, the effectivity of suicidal runs are limited, the roles between planes can diverge, and people will face the need to balance numbers between jabos and fighters, operating in the target sector.
Or, if they think that's too harsh for them, they'll give up the jabo role entirely, which means fighters will come in strafing fields - it will kill the fuels, yes, but it will need a lot of numbers advantage to suppress a field. Also, if they want to capture the field, they're not gonna do it any time quick by just strafing the town buildings(we all know how people hate to leave the vulch scene, don't we?)
So if one side has enough local numbers advantage, they will probably do the same thing without bombs - come in kamikaze, strafing the field.
However, if the numbers are matched, they won't just slip past defenses and go kill every fuel or every hangar, or every barracks or every ammo bunker with just two, three planes.
ps1) Better yet, if the field objects accompany some changes along with the above suggestion:
(a) The most important of all resources(fuel), is placed within armoured bunkers or depots requiring a couple of thousand pounds to kill.. maybe 50% of fuels in armoured bunkers, and rest 50% in normal drums..?
(b) Some objects, such as town buildings(which are probably made of wood, stone, or concrete) are impervious to machine gun/cannon fire under 30mm. Town buildings, armoured bunkers, vehicle hangar, shore batteries come into mind.
If those two changes are implemented alongside above suggestion, then I guarantee the suicidal madness will be a thing of the past. Jabo role, and I mean an effective, good jabo role, that almost instantly renders a field defenseless, fuel-less, GV-less, and town-down for capture, will be considered a thing for trained jabo specialists and good bomber pilots, as much as a2a combat needs skill.
Oh sure, nobody's gonna stop you or punish you from doing what you like to do. Except you won't make a dent to the defenders if you don't do it right.
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ps2) For more thinking, please look up my NPA linked in the sig. More detailed discussions on diverse plane sets and limiting abusive kamikaze tactics by means of perking, is discussed there.