Rolling is fine when it's used properly.
If you want to play a marksman as an admin and shoot someone in a group that bad, make them all roll and whoever gets the lowest under a threshold will get shot, not instantly die. Meaning if the threshold is 30 and everyone rolls something above 30, even if the lowest is 31, no one gets shot ; But if two people roll under 30, say 29, 20, the person who rolled a 20 gets shot but not instantly killed. Don't do some shit where you just pick someone and /event it.
If you are playing an event character you should not be able to no clip, look at two players who are trained on you, un-noclip, unlock a door with no RP, kill them both, and ask for rolls for wounds. That's when this roll system is stupid and people have a reason to complain.
If you use it as intended there is no need for this forum discussion to even take place.
When someone runs off by themselves, or is rambo'ing, just something really stupid, I say insta PK them because that's how it should be, discourage that behavior.
If someone is doing something rambo'ish within reason, perhaps a heroic moment where they should expect a possible PK, apply the roll system as we have it now.
If someone is meticulously acting everything out that they need to, taking precautions and the like, they shouldn't get fucked and if they are really in a position where they are going to, they shouldn't get fucked that bad.
TL;DR - Just apply the roll system fairly, there shouldn't be a standardized system that is applied to every situation because every situation is different. It also never hurts to ask the player if they are alright being wounded, critically wounded, or PK'd if the situation calls for it. These are simple things that can be taken into account and please a majority. I don't see the system of PK's changing drastically by any means, it doesn't need to to be fair, it just needs to be slightly altered to be more situational and that's how RP always should be, situation by situation.