I think its fascination lies in the fact that people are jaded with seeing the Parkinson/Jonathan Ross professional conversationalists. Similarly the endless procession of people who can't perform normal social functions in Springer/Oprah/trisha etc has also begun to pall.

The conversations on Big Brother may be trivial and sometimes stupid, but at least they are genuine conversations. they do not have this heavy subtext - (Springer - what a scuffler, let's laugh at him! Oprah - I feel for you, and you've written a book! Trisha - I can help with advice, but you must help yourself)

Its harmless.