Rolling Stone: No Love 4 Rap?

I recently caught an interesting list on the RollingStone.com site,the "RS 500 Greatest Songs of All Time". There's some great stuff on there and many which I'd say are as advertised, "greatest songs". But after a scan of the top 200 of this list I noticed a glaring issue; the lack of a rap song in the top 10. Check that, there's no rap in the top 50, top 100, or top 150! An interesting notion. Does Rolling Stone truly believe that no rap song is amongst the greatest? The first song I noticed on their list for rap was Public Enemy's "Fight the Power". It's definitely a great song, with a great message and political connotations. But in all honesty, if "Smells Like Teen Spirit" is #9, why is "Walk This Way" or "F the Police" or "Fight For Your Right" not mentioned amongst the elite? "Walk this Way" by RUN-DMC was the song that began the whole crossing rap into the mainstream of society movement. Beastie Boys' "Fight For Your Right" was doing the same thing, a rawkus rocking party anthem that many could relate to and love, and is still played all over today. NWA had just as much to say with "F-- The Police", even if some see it negatively. All 3 could be considered "Greatest Songs". The question is what were the criteria for the list, and why were these great songs omitted? To check out Rolling Stones' 500 Greatest Songs, click here.