The rap culture is heavily reliant on crime and violence as their marketing strategy . I refute your statement. It's not the culture but corporate media that sponsor this hardcore/studio gangsters genre which sells. Not the entire culture as a whole. If "conscious " rap was the major seller than their mostly will be a different view.
When I used the term "rap culture",I was referring to the fan base of the gangsta rappers. I know that the culture as a whole doesn't represent these values. As for the corporate media, guys like Tupac,Biggie,Flav,50Cent,Snoop,etc,were already criminals on their own without any corporate image making. They made a conscious decision to continue to write and produce the kind of gun,drug,and pimp crap that would make them money.
They could have chosen to make more positive product,but they knew that the fan base they needed wouldn't support it. I have no problem with this,and I agree with you that it is marketing. My point is that the Corporate Media didn't create the crime and violence driven genre,they just responded to it by giving the fan base what it already wanted.