re: Sadly they have changed..
Carson also had the class and wisdom to sit back and let the guest
be the star of the show, to say nothing of the often higher level of
guest beyond the usual bimbo starlet or actor. The current hosts
usually use their so-called conversations with guests to set up a
punch line for a joke.
Note that in the Denver-Sagan conversation, most of it was quite
interesting without either party feeling the need to make it funny every
few seconds. Refreshing.
When was the last time a scientist or similar figure was on one of these
talk shows? I remember Buzz Aldrin being on Letterman circa 1995 and
it was just embarassing the lowbrow questions and comments he threw
at the second man to walk on the Moon.