I would personally go with dropping the complexity a bit.

I believe what happened (I'm just speculating here) is that the falloff bonus was supposed to play a much more important roll to the Numquol when PO was in development.

In EVE (which PO is based off of) the Minmitar very regularly engage in falloff ranges.  Similarly, it was probably decided at one point that Numquol weaponry was to have extremely short optimals and extremely long falloffs (sort of like autocannons/machineguns).

Because that (obviously) never got implemented, the falloff bonus (both the main extension as well as the Numquol combat bot falloff bonuses) has very little effect in game.

Falloff in PO needs to be looked at and fixed before any cost changes to the extension itself.

the EVE copy part is probably on spot,

but the rest not, since the blue bots didn't have a falloff bonus to begin with. their development has gone through:
- turret range bonus
- railgun falloff bonus
- falloff bonus

in early times, even demobs had falloff ranges, but due to a problem with hungarian math, instead losing efficiency, demob had even greater effect the further out you have been hit in falloff range.

since turrets and missiles have exactly same number of extensions - "falloff" [4] is the counterpart to "missile guidance" [6] which was added later in the game (early missiles had 100% chance to hit)
all other extensions have exact same complexity.

if you look at this - falloff is a almost useless extension,
its there for firearms-user in blue bots, and since firearms got a lower complexity then other weapons, falloff has a higher one.

and missile guidance is a very expensive, later must have extension for missile user.

yay, a wonderfull example... especially since C&C was made by Westwood studios.
and dune2 was made by... Westwood studios.

can you actually call a successor game made by the same guys a "clone" ??
does that mean CS was cloned by CS:Source  which was then cloned by CS:GO
George Lucas has even named one of his films "the clone wars"

ok, joking aside - you can believe what you want, but most mechanics are rip-offs.
There is a reason why perpetuum  is called Robot-EVE, and that is not only because its the thame genre...