Because we're a television/media saturated culture, so many non-talents and wannabes receive way more than their share of face time and adulation.
With the passing of Johnny Carson, an American icon is no more. Yet, because of the very medium he was so intrinsically a part of, his clips will live on for a long, long time.
Yesterday, I saw a couple of wonderfully touching pieces on Carson, including some hilarious clips with Ed McMahon, his trusted sidekick, as well as one with a very young George Carlin.
Carson was an original and there will never be another. Maybe that's a mark of greatness and legend--the inability to clone or recreate a sequel or sorry ripoff.
Here's a great interview with the master, from 2002.