In Null/WH they have AOE effects, this means that their effects scale as the size of the enemy fleet goes up. Which acts as a multiplier rather than a straight scalar. Obviously AOE effects in high become difficult to apply, unless they automatically miss neutrals, which could be possible for the point defence.
In order for them to make for good defence in highsec, they need to get some kind of similar scaling ability, be it on their own abilities or on the ships supporting the citadels/etc. Something I’ve always wanted to see them get would be Command Links, as something that isn’t direct damage, but makes it significantly easier for a smaller fleet to fight in defence of their station.