Why haven't we seen any artists similar to Tupac and Biggie?

In my opinion Tupac, Biggie are the greatest rappers ever along with Rakim. But it seems like over the last decade there haven't been any rappers that are even on the same level as those 2 at least in my opinion. I don't know what it is, those 2 just changed the rap culture and it was like art in a way. When I listen to the top 40 on the radio and I hear today's rappers it seems like they can't even compare to those 2. Does anyone else feel that way at all? Its honestly wish there could be another Tupac, but there isn't. I just feel like this new generation music doesn't even come close to the 90s rap style.