But Justice is important.
In an environment where the corrupt and the rich and powerful not only perpetrate endless crimes for personal gain or lust, but have the capacity to buy, silence and upend the rule of law, foreclose the very avenues through which justice can be had, what is the way forward for those that lack the resources to fight back.
So I think they've shown not vigilantism, but a larger search for justice in a very crooked and unequal world. Durga and Dayal and Akram (and later Dev) do not stoop to mayhem or killing or the darkest deeds that the antagonists unleash but build the evidence that will turn the upended justice around. they could have "killed" shaurya, but it was only paralysis...and so on, and eventually justice will be awarded in a court of law, not on the streets.
They could have built a tighter and slicker narrative, but at the end, it is a public unmasking that this is about so that the truth is out in the open and justice can no longer be denied. THere in lies the "greater good" but it will surely not be "cost less" -- Dayal and Akram may end up paying the ultimate price, and Durga/Nitya as well in her own conscience (wrt Dev at least, and even Payal, and Dayal and Akram if anything happens to them).