Aside from the fact that while yes, a lot of mainstream rap these days is about money, as with most mainstream music, Nas is far from the only person left peddling true hip hop.
Also, this is exactly the point, if you only pay attention to what you see on MTV and the like, of course you're going to see <img src="/xxx.gif"><img src="/xxx.gif"><img src="/xxx.gif"><img src="/xxx.gif"> music. You're also going to be talking <img src="/xxx.gif"><img src="/xxx.gif"><img src="/xxx.gif"><img src="/xxx.gif"> if you base your opinion from what you see on MTV and other channels like it and the subsequent radio equivalents.