(and i'm paraphrasing here) but he once said that alot of hip-hop artists make hip-hop with the mindset that they're acting one step from being back in the projects and i think the mindset you are suggesting is that of someone who either is investing in their craft or has the luxury of being an artist because they have something to say.

plus there's seemingly no artistic integrity self-policing hip-hop to make a sustaining market for more 'left-of-center' acts. it was present in the golden age and even for like 3 or 4 years in the 90's but in the post-Chronic days, everyone's looking to make something that sells rather than make something that lasts.

i know alot of the hip-hop we adore and worship (Tribe, The Roots, Illmatic, Pete Rock) was made with a sense of artistry and integrity, but alot of producers are in hip-hop to make a buck over doing something noteworthy, at least the commercial ones seem that way.

with the costs of sampling steadily increasing and the variety of music being commercially viable decreasing, it seems like there is less and less of a chance of a collective of producers or even a single producer choosing to actually experiment and try something like you're talking about even though there might be a market for it.