2004 marked the end of Friends and Frasier, which was seismic for NBC obviously but also for television. Comedies have rarely been monoliths ever since. This was kind of the death of "Must See TV." But it was also the heyday for me growing up with television. And I don't really recognize the massive Friends phenomenon model anymore anyway.
The Worthies: Jimmy/Timmy Power Hour, Friends finale, Lost pilot, SpongeBob, Deadwood