Heyyo, folks!
As long as weapons continue to scale linearly (which they do, confirmed by Lancake and other testers in the bug tracker), Gigantism will always be a crippling gameplay issue. I've argued with others such as Calbiri and Mr.Furb about eliminating it, but they refused every time. Not to be arrogant, but they simply don't understand the nature of combat as we do.
Linear scaling on weapons was kept due to the non-linear scaling of power acting as a limiter. The biggest issue with offense vs. defense balance I've seen is that power capacity oriented ships can almost invariably one or two-shot enemies of a similar size because it's possible to dump a billion energy into offense all at once and it isn't possible to match that type of burst power with defensive tools. Shield capacity blocks add... Usually less than 50 shields (500 energy's worth of shielding vs weapon fire) scaling down based on how many you've got. Slowly, but still.
Compared to a weapon block's average 5 DPS that's not too bad. Ten seconds of protection? Rarely is that the actual case. Other factors such as ion/overdrive, pulse, and base rearm speed allow each weapon block to out scale the protection of shielding in single volleys, their only limiting factor being power.
Power is the enabler of the problem as far as I can tell. Power capacity blocks have a base 1000 power multiplied by (number of units in the group)^1.05. With weapons taking 10 energy per damage point, that gives each power capacitor a value of over 100 shields. Scaling up. Paired with a high reload or specialized anti-shield weapon, you can make a combined power/weapon system more effective than a power/shield system ten times it's mass.
While weapons and their counterpart defenses are technically scaled against each other DPS-wise, there are way too many multiplicative bonuses for weapons that shields can't take advantage of.
A quick'n'dirty solution would be to simply increase base shield capacity to take this into account but that would negatively effect the cases where offense vs defense is actually going as planned, such as... Er, any weapon with a reload anywhere under ten seconds.
A concept I'm toying around with is a change in Ion's defensive behavior to base it off of infinitely scaling power capacity instead of power regen. Instead of hardening your shields by a % (extra protection based on how many shields you already have) it turns a large portion of damage against shields into damage against your power. This allows defenses to tap into power pools in the same way that weapon can. Exact numbers are impossible to come up with until there's actual tests on the matter, but I'd imagine it being somewhere close to this:
<DefensiveBasePowerConsumption>5</DefensiveBasePowerConsumption> <!-- Power cost per block per second, % bonus is based on the system/ship mass size ratio -->
<DefensiveBaseMultiplicator>12</DefensiveBaseMultiplicator> <!-- multiplied with effect block count -->
<DefensiveEffectType>STATUS_SHIELD_LINK</DefensiveEffectType>
<EffectConnectDescription>Does extra damage against shields,\nbut less against blocks</EffectConnectDescription>
<EffectIgnoresShields>false</EffectIgnoresShields>
<DefensiveEffectCapPercent>0.8</DefensiveEffectCapPercent>
<DefensiveEffectEfficiency>15</DefensiveEffectEfficieny> <!-- Power cost per point of damage reduced -->
What all the jumbled mess above is stating is that at 100% efficiency, this would take up about 8% of your ship's total blocks and cost 5 energy per second per block. It would cause 80% of the damage dealt to your shields to be absorbed at the cost of 15 power per damage point.
Even if your power systems are inferior to your opponent's you can still dent their shields with enough pew pew. It'll just buy them time. Trying to use this against someone who outmatches you will only lead to you being completely helpless as your power drops to 0. Burst weapons will still have catastrophic effects, but will no longer immediately end fights.
Hopefully.
On the subject of gigantism, I personally like that there's huge ships. I don't like when they're everywhere or when they're the only option. A proper economy takes care of one of those, and a difference in stealth play and maneuverability should take care of the other. It's not satisfactory yet, but I'm sure that continued pressure in the right direction will get us there eventually.