I'm not exactly sure, but if I were to take an educated guess as an observer, I wouldn't put it down to a hip-hop message of urban oppression blighting a mass population that can be identified with in the purest sense as a general thing, especially in this day and age. There's no denying that hip-hop was once a pure expression of descent and disdain encapsulating much of everything that was wrong resulting from inner city urban oppression, deprivation and poverty for black communities within the US. But I reckon there are very few hip-hop acts that have that kind of authenticity characterised and awarded by a contextual frame of time that has for the main part passed in its most severest forms. There's no way that you could have a modern equivalent of NWA or Tribe called quest for example. Even the original RUN DMC weren't that well recognised in their day outside of hip-hop circles when hip-hop was nowhere near as big as it is today, at least not big enough to be rolling triple platinum as hip-hop superstar millionaires despite now having legendary status today within hip-hop. Why have I missed out a whole bunch of other seemingly very credible big name superstar hip-hop artists? Because it wasn't until after NWA went big did record companies and record producers begin to realise the formula for what made people buy hip-hop records in their droves beyond a niche crowd which many hip-hop artist played up to even more so in order to sell records. At which point it almost became ok to be on death row having committed gang related crimes and murders because you could sell records, and because...well, you had committed gang related crimes and murders and could rap which only boosted the image and the sellability of a gangster hip-hop superstar rapper even more so. 

The popularity of hip-hop is a contradiction in itself, because the vast majority of people and fans who were actually buying hip-hop records, tapes and CD's (as in people paying for legit copies that the record companies could bring the money back in from) weren't necessarily from a background of urban oppression or decay, at least not in the old-skool pre-mainstream controversy producing NWA sense. 

I'm inclined to think that initially Hip-hop wasn't something that sold to a mass audience beyond its niche routes because it was necessarily delivering a message that a vast majority of its paying audience could identify with in terms of experience, I'd be more inclined to think it was the controversy itself more than anything else, and its then none mainstream explicit lyrical content and facets of it that reflected a rebellious anti-establishment energy that a non-black and black youth generation craved that was different to the main-staple of rock'n'roll. Even if you look at the roots of rock'n'roll, that too was originally a black music movement that came from the blues before it was adopted by the mainstream in its time to then be predominantly fronted by white artists for Elvis to become the "king" of, from which you now have all the variants of rock'n'roll today for it to now forever be associated with rebelliousness. 

But back to the point, it wasn't until you had this mainstream popularity of hip-hop in the US did it begin to feed back into the wider society as a more general representation for urban oppression by other black youths who probably would maybe not necessarily have got into gangsterism but were also black, were very familiar with the decay/deprivation, and last but not at all least, were also very familiar with racism. Not to mention other significantly large ethnic groups who also began to buy into hip-hop before trying to form their own variants.

I also think the term ethnic minority is miss-leading these days, but that's another can of worms for another day. 

What do rappers rap about these days? Having a good time whether in its more direct "gangster" or indirectly "gangster" forms? Maybe if sticking to purely Gangster forms trying to get rich, being rich and hedonism? Oh, and I almost forgot, "being real" with references to the tribalism of gangsterism? Being angry and controversial? Beyond that you've got your other slightly more positive feeling/worded hip-hop which is generally a little more conscious whilst trying to be the antithesis of pure gangster hip-hop?

But I think these days its turned more into a game where you pick a side to then do psychological battle depending on which side of the line you want to be on at any particular time.

Being a superstar rapper was something that was aspired to in the US much in the way that many people wanted to make it as rock'n'roll superstars. What they were saying also resonated with the youth of the time hungry to feed a rebellious streak on various different levels beyond its original core expression depicting a racial struggle amidst a setting of urban decay and poverty. Using rhyming words over a dub on a record without needing to know anything about music, music production and not needing to be able to sing as the "raw" skill? How difficult could it be? Its seeming accessibility in being able to pick up and just do to say whats on your mind regardless of how good you actually were at it must also have been part of its appeal and draw. Superstar rappers originally from some of the most deprived walks of life rolled triple platinum whilst the record companies got even richer and made even more money. Those rappers then set up their own labels and made more superstar rappers hungry for the limelight. CD's went big at a time when MTV was pushing it and the internet didn't exist for the mass consuming public to generically access, which also further ensured megastar millionaire status amidst a relatively small list of superstar rapper names if you did make it.