Truth is, Conan O'Brien just isn't good enough. Honestly, I tried to stomach his sophomoric humor when he took over the Tonight Show, but gave it up as hopeless.
O'Brien's supporters seek to portray him as hip and sophisticated, and that the folks who prefer Leno as uncool. I spotted this illustrative post on Entertainment Weekly from Brenda:
hey chevychase, a little lesson in how network television works. leno
was the bigger draw because he had a better prime-time lead in, when
NBC used to be a decent network with good dramas on at 10pm. conan's
problems (and NBC didn't view them as HIS problems, incidentally) were
because leno's show was pulling horrendous numbers (notice they
canceled jay, NOT conan). NBC knew that conan needed time to grow an
audience because he was largely unknown to the unwashed masses who
appreciated the tonight show with jay leno. conan is too smart for
network TV. the only reason he did well at 12:30am is because
censorship rules change after midnight and he was allowed to do "his"
comedy. he needs to go to cable to do the kind of show conan fans would
really appreciate. [Emphasis added.]
Leno beat Conan in the ratings, which in the minds of the elite is a bad thing. Conan, waiting all those years to sit in the Tonight Show host's chair, blew it.
Conan's whining about how he won't be a party to the destruction of the Tonight Show is as sophomoric as his comedy. Brenda is right; he's probably better suited to a niche audience on cable. Call it High School Comedy.
Below: What was said before Conan started and some insight to why he failed.