I think the biggest problem is that people's taste in music is to diverse and distinct. The beauty of Generation Y/iGeneration is that it is extremely easy to move on from mainstream music and acceptable to be an indie snob or a metalhead or like underground rap.
That said, I would say that Jay Z is the voice of this generation. His body of work is varied, and he is one of the few to have mainstream, commercial, critical, and popular acclaim. He has also been able to not fall into the cliche of being a rapper, as he's avoided petty feuds, legal trouble, and turning into a parody of himself. His collaborations are usually smart, and he has been able to crossover to the TRL crowd, most rap fans, and was even getting play on rock stations with "99 Problems" and his collaborations with Linkin Park. Look at his musical accomplishments, like running his record label, opening restaurants and clothing lines, and being a co-owner of a sports franchise. He's definitely changed the perception of what it is to be a successful artist.