Most people by this point know either subconsciously or consciously the main reasons for why CNN, MSNBC, ABC, CBS, and Fox News regulars act like a group of preppy high school girls. Let's briefly list 4 common reasons before moving on to the underlying explanation.
1) The nature of their work as charismatic and believable presenters of information rather than experts. It is key to mention that the separation between 24 hour cable networks and brief "serious" 6 PM broadcasts on basic cable is disappearing. It used to be that the evening news audience demographic was numerically dominated by the group of elderly depression era females. This explained the need for senior citizens like Dan Rather who was ideal marriage material for the widowed viewers and delivered the authority of a small town doctor. To this day a doctor is shown by polls as the most respected wage laborer whose opinion is considered the most truthful (it makes doctors natural lead characters in TV drama series and movies). However this demographic is dying off and being replaced by baby boomer women (greater female life expectancy always tilts corporate marginal profit seeking) who respect Katie Couric's professional achievement and ability to look good at her age.
2) Support by biggest media corporations of Reagan's efforts to reduce funding for department of education (either through cheerleading it or tacit support from silence). 40 year olds watching the news on TV today were directly affected by the across the board reduction in quality of schooling. Television and newspapers thus have to use less big words and their writers are increasingly relying on baby speak, puns, and outright prepackaged talking points (Gretchen Carlson playing dumb to keep her job is one extreme example of this). Shorter attention span is not the cause but the social symptom. This directly feeds into 3)
3) MSM responding to an Australian tabloid oligarch's invasion of United States with headlong rush towards turning news into entertainment. Of course this would have happened even without the accelerating influence of Rupert Murdoch's News Corporation conglomerate. The aging of current TV demographic is permanent since mostly those remain who are unable to master the use of internet two way transmission medium. Since the audience is increasingly represented by rural senior citizens who were failed by the education drives in the 50s and 60s, the intensification of circus style hysterical entertainment as seen on the radio is inevitable in the short term. Murdoch's influence must again be mentioned however. Newstartainment ( trademarked =] ) saw a publicly visible deepening split between internationalist media oligarchs (who encourage globalization since USA is not essential to their base of operations) and nationalist media oligarchs who use their media asset influence to help out USA based heavy industry. NBC Universal can be said to be an example of a nationalist oligarch mouthpiece since it is owned by General Electric (which is reliant on selling real tangible items like engine parts to US military and government organs). News
Corporation of course is not as reliant on the well being of United States military-industrial complex so its assets like Fox News can be extra irresponsible with their newstartainment. From the financial perspective it is better strategy for GE's bottom line to support nationalist Democratic party wing of the oligarchy (since better educated/healthier peasants allow US based corps to better compete abroad). That is why MSNBC leans towards democratic millionaires and their businesses. The fact that Fox News was emulated points less to its success than to a transition of formerly US tied corporations towards a more global status. For more information on who the top 10 owners of media clusters are, here is a handy chart (warning: This is from 2002 and the industry got more consolidated and monolithic since then. Use it to get the thrust of the idea).
4) Losing ad revenue to the internet since television news (and TV programming in general) did not live up to its promise of raising human consciousness as envisioned by the first head of the FCC. The internet serves as a type of American glasnost while television serves as a way to sell state propaganda and mass produced TV drama garbage at home and abroad. That is easily recognizable. Getting young people's trust back (to keep going long term as old people die) is now almost impossible and the road of least resistance is to intensify the circus. Some young people watch the news and MTV just to laugh at how terrible it is (that still is a mild boost to ad revenue). News "anchors" themselves do not come into contact with relevant information much since their networks have actively cut recruitment of journalistic investigative talent. Since it is cheaper to analyze second hand information with talking heads than hire sufficient numbers of understimulated human explorers (and pay for their plane tickets, hotel accommodation, security, etc), news anchors come less and less into real contact with knowledgeable experts. Ridiculous cowards like Wolf Blitzer for example, do not get hits to their self esteem as much from interaction with resident stay at home talking heads than with old school journalist data fiends like Michael Ware. To be fair, as Fox News anchors show, there is a lot of self censorship and dumbing down to remain on the job.
And the underlining explanation is....
National news anchors and pundits are members of the wealthiest 5% or 1% of the population.
Even if they started out poor (which is increasingly becoming unlikely as key people in the conglomerate hierarchy flood these simple job openings with their children) the long cut throat climb to the top irreparably changed them. The laughing playboys on TV are completely insulated from vast majority of the problems that Americans are facing (except of course problems of taxes on income and capital gains and regulations on financial gambling). Whether they work for Fox, CNN, MSNBC, many of them are good friends and are always on the look out to jump ship to another network to bump up their salary. People like Anderson Cooper, Lou Dobbs, Sean Hannity would never be caught dead riding a piece of third world joyride called the NYC subway.
To them life in America is great and getting better all the time. Every day is just an ego bolstering practice of either driving from luxurious suburbs or being driven to a place where people put make up on them, where they see their friends, and where they talk to some senior citizen politicians/celebrities (who are naturally as insulated). They sit down and chit chat about the problems of places like Detroit ( which for all intensive purposes is as foreign and distant as cities in Africa are). They are goofy and full of giggles not just because they are professional entertainers but because the anchors that elderly people get their "news" from are but middle aged preppy high school girls on the equivalent of a fashion show.