The first and foremost factor is this: it's just a job to them. They have to put out a news program (1) to be taken seriously within the business, and (2) to compete for a small but elderly, loyal, and relatively wealthy audience that tunes in the nightly news and doesn't channel surf during the commercials for Polident, Depends, and all the drug ads.
But at the end of the day, it's just a job. Going conservative, or even "fair and balanced," is rewarded by the good thoughts of millions of American conservatives, who channel surf anyway, and who's good thoughts are worth absolutely nothing. It's also rewarded by millions of hate-mail letters in the mail room, field reporters kidnapped, held for ransom, and killed, as well as the very real threat that some unhinged moonbat leftist like Ted Kaczynski will light off a truck bomb outside their headquarters building.
The people who run television networks are just schlubs who go to work every day. They prance and preen about how courageous they are, how they "speak truth to power," but they only speak truth to power they know they're protected from by the First Amendment. At the slightest hint of any real retaliation, physical retaliation, they'll fold in a split second. And they'll hand out awards to themselves for their courage while doing it.
CBS remained in third place throughout Dan Rather’s years as anchor, but could always hang their hat on the fact that they hired the guy who went against Nixon one-on-one when he was White House reporter.
Les Moonves could care less about good journalism, unless it’s linked to the entertainment division. That’s what you get with 60 Minutes on Sunday — the reporters are the stars, the little guy is brought out to showcase their anti-goverment or anti-conservative agenda -- with Bradley, Stahl, Wallace, etc. being the center of the piece.
I hadn't thought about it from your perspective, but you’re right. They don’t care about news ratings (but they do care about negative publicity that gets attached directly to Moonves, so she’ll be gone soon).