I think it's more complicated than just that network executives are reluctant to take risks. "Risk" is inherent in free market capitalism and enterprise. No risk, no gain, as they say. And it has always cost a lot of money to put toghether writers, producers, actors, all the equipment, stage sets, etc, etc.
From studying history extensively, what I've seen is that in many cultures, there will be these epic periods of explosive artistic and creative energy, followed by creative atrophy, apathy, indifference, and mediocre banality. The mid-late 1950s thru til the mid-late 1970s was one such era in Western history of dynamic creativity.
Look at what came out of those two decades: I Love Lucy, The Honeymooners, The Outer Limits, Twighlight Zone, Pink Panther, all those great Warner Bros. cartoons, Star Wars, Star Trek, Richard Pryor, Steve Martin, George Carlin, Johnny Carson, Sesame Street and the Muppets, The Beatles, Led Zeppelin, The Who, The Doors, Jimi Hendrix, Black Sabbath, Cosmos, Bob Dylan, Spiderman, Heinlein, Asimov, Playboy even, all the Hannah-Barbera cartoons, the Allman Brothers, Alien, space artists like Bonestell, Hartman, and Miller, the Monty Python troop and Benny Hill, so much high quality, explosive creativity AND originality.
And now, and for the last ten or more years, all we seem to have is rather flat imitators and outright copy cats. I'm certainly not saying that it's all bad, (early "Simpsons" seasons and "South Park" are great) there's always great art to be had, but the energy seems to have dissipated for now. Perhaps we will all live to witness, and be a part of, another creative flowering.
And while youtube is a great idea that can give fledgling artists and film makers a leg up, it also leads to over-saturated over-kill. Twenty years from now, everyone will have their own television station. Like almost everybody is already getting their own website. :lol: