Reading an article in the 10/27/09 NY Times about your declining ratings, I wondered why my wife and I used to watch you nightly without fail, but now watch you never. (We've been driven over to the Lehrer News Hour, soporific though it can sometimes be.)
It's not you, Mr. Cooper. We continue to like and respect you -- or rather, your TV persona -- and you rate very high on the Cosby/Cronkite scale, the measure of how much we want a TV personality to join us in our home every night. (Christopher Walken's a compelling actor, but as a news host, he wouldn't last two broadcasts.)
I've come up with several reasons, most of them doubtless no news to you; but if even one offers a fresh idea, I'm pleased to donate it. In no particular order then, I think your numbers fell because:
Tabloid headlines filled the gap. Michael Jackson and the girl kidnapped and held 14 years etc. etc. were undeniably news of a sort; but to milk them day after day -- and sometimes week after week -- quickly irritated people who's IQ numbers are higher than their ages.
Endless repetition substituted for the effort and expense of covering additional news. The rest of the world was squeezed into 60 second mashups while the megillah du jour was rehearsed again and again. The visuals themselves were maddeningly repetitious (If I see Madoff led into court just one more time!).
Computer enhancements grew more and more manic until the screen boiled with meaningless color and motion and audio transitions whooped as if synthesizers had just been invented. Circuses are equally loud, frenetic, and gaudy, but I can't take their hoopla five nights a week.
Together, these changes produced one fatal result: your broadcast lost its essential identity as a news program.
Adding wingnuts like Fox or seizure-inducing graphics like E! will only destroy the remnant of integrity that Anderson Cooper 360 retains. Instead, why not restore the format of a true information hour? Present a wide variety of news. Keep those studio Steadicams moving but spare us fake backgrounds full of clocks and monitors. Above all, dispense with pundits who sound like spokespeople for political lobbies. Give us variety in viewpoint and opinion, but see that it's thoughtful and nuanced. (For instance, though I'm a Progressive, I listen to David Brooks with respect.)
Will this prescription return you to the top of the cable news tree? I don't know; but as the old lady said about giving chicken soup to the man who'd just died of a heart attack, "It couldn't hurt!"