I don't think its because large ballistics are bad. I think its because large ballstics armed ships have divergent mounts. The Conquest with its broadsides, the Onslaught with its kind of 2.5 broadsides (as each forward flank can support 2, but only 1 forward + TPCs). The issue that was coming up was that it was better to concentrate the OP power of a ship in a single direction and then point that way: single broadside Conquests, forward only Onslaught (or even broadside onlsaught with 2). The large mounts in the off directions then got like a single flak. Heavy Ballistics integration incentivizes keeping those "off" mounts still filled with larges instead of downsizing them. The ships with large ballistics without divergent mounts (Dominator, Legion) don't have HBI.
HBI is definitely this.
However as an aside i am struck by how hard it is to armor tank large ships anymore(absent derelict contingent armor tanking). Impact Mitigation is... much weaker than it used to be. And, importantly, comes at a huge loss in DMG. Shield tankers have an advantage in that they can reset their effective HP, so -20% damage is a pretty strict bonus. But armor tankers cannot, and so need a much larger effective increase in general. The problem is that impact mitigation is far weaker than armor tanking used to be in net.
And, importantly, its far easier to increase hit strength. The general hit strength advantage an officer has now is between +20 to +50%(for a frigate this can go as high as 70% though its unlikely). While the general bonus DR that an armor tanker has is -25%. This nets to a 10% advantage to 12.5% deficit in terms of hit strength*. And its worse if you want your large armor tanking ships to actually do damage. Because armor tanking is now on the same skill as a +30% damage bonus from range. So an armor tanker compared to a shield tanker, capital officer vs capital officer, now has a 12.5% deficit in terms of hit strength/dps over no skills, but also has a 4% DPS deficit. (Shooting 1.2 weapons into .8 shields) for a net 17% disadvantage over no skills. And this without having a unique top of the line value for the tier 5 skill (where as mid tech and high tech generally do).
This is a far cry from the advantage you could achieve last version.
On top of that the inability to easily get PD on armor tanking ships
*While there were much larger hit strength bonuses in .91 these were entirely offset by the armor strength bonus. So we can effectively ignore them in net x/(x+y) = x*.5 / (x*.5+y*.5). Thus we had the +15% dmg skill vs the +150 armor always skill and the 90% armor DR skill(and maybe another -armor damage taken skill i think?). You needed about 500 hit strength before +15% damage would overcome +150 armor at 2000 armor as an example. As armor goes down the necessary hit strength bonus to achieve equivalency goes up.
To compare:
.91 armor dmg bonuses were +15% (all dmg) +50% hit strength, +50% weapon/engine dmg
.91 armor tnk bonuses were -20% armor dmg, +50% armor calc, +150 armor, 10% minimum armor dmg calc, -50% kinetic dmg, -50% weapon engine dmg, +50% weapon/engine repair, +50% weapon HP
.91 net(officer v officer) armor tanking was -8% incoming dps and hit strength, +150 armor at all stages of calc, 10% min armor damage calc, -50% kinetic dmg, 62.5% effective dmg reduction for weapons/armor, +25% repair rate for weapons/armor
.95 net(officer v officer) armor tanking is +17% incoming DPS*, +12.5% incoming hit strength, +50 armor at all stages of calc.
Relative DPS change:
+27% (
not including secondary characteristics OR hit strength)
.91 Shield dmg bonuses were +15% (all dmg), +15% (Shield dmg)
.91 shield tank bonuses were -20% dmg, 10% hard flux dissipation while active, -25% HE dmg on shields
.91 net(officer v officer) shield tanking was +5.8% incoming dps, 10% hard flux dissipation while active, -25% HE dmg on shields.
.95 net(officer v officer) shield tanking is +20% incoming dps*, -30% HE dmg on shields, 15% hard flux dissipation while active
Relative DPS change: 13.4% (ignoring secondary characteristics)
This is a huge discrepancy. It used to be the case that an Onslaught could keep firing its weapons when taking armor damage. This is not possible anymore even with armored weapon mounts and automated repair units. Ion damage disables RFC, AWM, ARU ships now when it generally did not as of last patch. Not only did armor tanking receive a much larger effective deficit but the secondary characteristics swung away from armor tanking and towards shield tanking. (with the lone exception that building in Heavy Armor on everything is now hella good). Whenver i am building armor tanking ships armor tanking has to be a secondary consideration over making a good shield tank and using both (unless utilizing DC... but even then without the huge DR on weapons .91 provided DC just means you get disabled and killed)
*this assumes that the target shooting at them is a shield tanker and not an armor tanker in both cases armor tankers generally lose out on a 0 to 30% damage bonus as a result of taking impact mitigation.