While KRS is indeed a key individual in Rap, I don't understand the concept that just because you listen to the genre, you have to know who he is. If you enjoy watching comedy movies of today, must you know all the key players in previous eras? It's not as if when you start listening to a genre of music, you're forced to take a history class to understand where it's roots are and such.
It's music. People listen to it because they enjoy it. They don't have to know who Kool Herc is to listen to 50 Cent. Or know what someone is talking about when they mention "Rapper's Delight", just because they may like "New York State Of Mind".
Now, move along.. hip-hop elitists.