
I'm not going to attempt to discuss paleolithic cave drawings, but yes some people might trace that the origins of cartoons as we know them. I'll instead start with the growth of the Disney Company and Warner Brothers. In a nation that so firmly roots its heritage on patriotism, it does not take much to discern the intentions of this war-based sketch involving Donald Duck or this one of a less than elegant Bugs Bunny. No it did not help that Yosemite Sam was a Confederate soldier either. So I'm guessing the basis of cartoons was to be a (not so) subtle 'persuasive device' for America's youth. While also serving as a fairly decent advertising stump for emerging companies to sell their products to kids, like Winston Cigarettes.

So what was really at the base of cartoons, a government interested in raising nationalism or Joe Camel's forefathers hard at work?

I'm sure most people enjoyed the Flintstones, but can you actually find anyone that saw the original airs of it today? I know I grew up watching it on syndication, and without the Winston Cigarette ads. It can be argued that cartoons needed to decline for social reasons. there was war at hand! Vietnam took a front seat and marketers needed to find a new venue from which shout their production cries.
Fortunately war ended, although GI Joe apparently will never age.

Cartoons eventually were relegated to Saturday mornings and a mass of quantity arguably began to override quality. I won't delve into psychological attention spans and that sort, for it on its own is worth great consideration. But think of this, a BRIEF list of Looney Toons easily eclipses 50 characters. The idea of absolutely manufacturing brief ~8 minutes sketches is essentially geared towards making a quick impact, while the multitude of these segments sets a decently consistent foundation. T
he idea of a single 3 to 4-group core maintaining the attention of a child for 30 minutes in the 1980's was preposterous. Unless you rented the VHS.At some point, I can't personally remember when, sketches began to decline. I'm not giving a straightforward reason, just conjecture, but I'm guessing marketing and the FCC had a hand. TV programs used to be 25-26 minutes. A decreased program runtime to 21-22 minutes allowed more time for ad placement and also made it plausible to stretch the limits of young attention spans 2 more minutes without risking the loss of cohesive plots. How do you stretch those extra seconds? Cliffhangers...no not Sylvester Stallone.
Sure Cliffhanging a kid could have dire consequences, but none that couldn't be alleviated with newer products and more importantly the increased marketability and novelty of main characters. Why would you want to just watch Ash, Pikachu, & company conquer a new foe when you could do it for 'real'? Branding apparently just went HGH on us all and achieved a new stratosphere of ability. Interaction and programming blocks dedicated specifically to certain age demographics began to blur the line of between watching TV and 'play-time'.
Which brings about an even more alarming idea: when was the last time you heard a small child engaging in completely imaginary behavior and not something based on a cartoon, TV program, movie, etc? Are we living in an evolving culture that now literally fails to think 'outside the box'?
My point as always is such: THINK ABOUT IT!