Clearly, this is what actually killed the roleplay. When people get told what they're doing is wrong, they bring the past shit and make fun about it instead of suggesting new ideas that would actually help, Subhan in other words, if you have nothing important to say other then starting a pointless argument, get out of here.
Back to the point. I believe, the players started to be more money-hungry as Matthew mentioned above, they all care about fame, money, and shooting like a bunch of animals. I think this issue started when you guys gave the players more script (get knocked before death, /rob, ability to rob guns, /frisk) and I cannot blame the management for implementing such scripts because obviously it was supposed to be rpish, players were supposed to roleplay frisking/robbing. This has been going for long lately, and I have seen administrators even do such actions and instead not punishing the players for doing it. Players must be forced to roleplay injuries when knocked, period. Criminals obviously don't care about dying literally, why?
What I would suggest: Making criminals lose huge amount of items and/or increasing the price of the weapons (or anything else that they would care about much) I think this is the only solution to make criminals think straight instead of being careless animals who fight till death and starts shootout when it's not needed.