I'm going to quote your number of 11.85 DPS...personally when I do the math I'm getting 10.8 but either case it is somewhere around 11 DPS...
Let us grant the range increase to Ruthlessness that I'm advocating...make it 7000m or 8000m, and let's just assume that range is good enough to encompass most it not all of the enemy fleet (which is not unreasonable since your own destras will be spread out)...
11 DPS being done constantly to at least 24 ships (or more depending on number of progs) may not seem like a lot....however, as you noted FFing is big in sins and so most of those ships will be at a low shield mitigation (15%)...so, let's just underestimate that to be 9 DPS...in one minute that is 540 damage done to each of those 24 ships...add another minute, or add another prog, and you can quickly see how that damage can add up to quite a bit...couple minutes and many frigates will be killed outright despite not actually ever being fired at...this is not any different than how malice currently works...it spreads out damage to the point where you get a cascade effect because all the remaining enemy ships have really low health...
Obviously even with the range increase there are some limitations...you need to have a prog with malice, and preferably a level 5 so you can have malice level 3...but, the ability is still contributing in a meaningful way, and unlike the other two abilities it can affect structures which do not generally have shield mitigation (excluding Advent)...
Let us compare that to the Kodiak's or the Enforcer's abilities...
The Enforcer's ability has a range of 4000m...like ruthlessness, that is a very limiting number...also, this ability does nothing against structures...while slowing down ships may slow their retreat, the range on this ability inherently implies that the enemy ships are in weapons range...so, it is not preventing them from killing you by reducing damage or something...if you are losing, or the battle is really close, this ability is not going to do you any good...
The Kodiak ability, like the Enforcer's, is only useful for chasing fleeing ships...and like the Enforcer's ability, this ability is completely useless during a pitched battle...
In both cases, neither ability helps you directly win a battle...they can help you capitalize on a battle you've already won, but only ruthlessness actually helps you win in the first place...in very unique situations these abilities may help you kill a fleeing cap that has taken damage (so, there is no implication that you've actually won), but in general it is actually advisable to focus on fleets before caps...and if you are choosing to focus on a cap, then you should have enough firepower to do it fairly quickly, again making both of these abilities not very useful....
In the end, none of the cruiser abilities are all that great...they all have a chance of tipping the scales in your favor, but all three have severe limitations, mainly their utility and their range...
However, a range increase to Ruthlessness would increase the effectiveness of it (since right now many ships often aren't in range)...and combined with malice, the damage that ruthlessness does is actually considerable...
The only issue with Ruthlessness other than its range is that it's a level 7 technology...like the overseer's abilities, while they may be somewhat useful in a particular situation, the tech cost simply does not justify the benefit...but, I'd say that applies to the other HC abilities as well...