Roger Ailes had a problem They had no audience yet and most cable systems would not put them on. CNN is paid by every cable system they are on, 25 cents for every subsriber. It matters not if they actually view CNN. CNN gets paid 25 cents a month for every cable subscriber that that can get their channel.
To get on the systems Fox had to agree to be paid nothing for 10 years. So the parent companys had to pay the entire costs until they had enough audience to generate advertising revenues.
Female newscasters are plentyful and they don't get paid as much as men. So Ailes hired females to deliver the news. He hired pretty ones over ugly ones, hoping channel hopping males would stay to watch his news babes.
Babes are cheap and attract the attention of channel flippers.. that is the story. Now everone does it.