If you think 200% more damge won't fix it test two supposedly even fleets, before buffing with +200% damge and then after.
-In short range matches, where both the target and the missile bearing fleet engage and fire at the same time, the time to effective dps drops for missiles.
However in optimal range, where missiles almost always have longer range - They get a volley in at the same time or before depending on the weapon. Therefore it depends on engagement range, a situational advantage - which is a good thing in my book.
-While missiles do overkill, it's avoided by spreading fire to more targets, and how many volleys to kill say a battleship compared to a corvette. Because the targeting data takes into account the maximum HP of the target. It spreads damage less against battleships, and more against corvettes. Because of this it often takes multiple volleys from a proportional amount shooters to kill any target. Because of this the overkill damage isn't large enough to cripple the fleet, it's the lack of raw damage from the missile weapon.
The damage spreading is proven here: I pitted 25 Battleships with Large missiles against a fleet of 75ish corvettes
View attachment 241497
Therefore buffing missile damage will spread any overkill damage further and instead of increasing overkill, reduce the time to kill the opposing fleet instead.