The range is tricky, yes, but they do have fairly high durability (mkI: 24 million cap-health, 750 armor, the only normal types with higher effective cap-health are ShieldBearer, ArmorShip, Laser Turret, Antimatter Starship) and their maximum cap dps (with efficient aoe application against things it has a bonus again) is about 1.6M. Against stuff they don't have a bonus for they still do 672K, which is the highest of the normal fleet ships, turret, and starship types other than a few types that are either kamikaze or fairly situational to get efficient application from (specifically, ZenithAutoBomb, SpireMiniRam, ZenithPolarizer, ImpulseReactionEmitter, LightningTurret, ZenithBeamFrigate). And that advantage actually gets higher at higher marks because they can hit more targets per shot at II and III.
Anyway, I don't mind buffing the range a bit, but the fact is that flaks have very nearly the highest durability AND very nearly the highest damage of the standard fleet ship, turret, and starship types. So they need some kind of counter-balance.