Short answers, pulled from the story.
Animation production shifted from theatrical shorts to television blocks in the 1950s following the Paramount Decree. This transition changed how people understood animation by the end of the 1960s.
Action programming was removed from the Saturday-morning slot after pressure from parent lobbying groups like Action for Children's Television. These groups voiced concerns about commercialism, violence, anti-social attitudes, and stereotypes in cartoons.
The era of half-hour toy commercials began with He-Man and the Masters of the Universe in 1982. The format continued with series such as The Transformers and Teenage Mutant Ninja Turtles.
Multiple factors contributed to the change including a competitive market fueled by multi-channel transition and a boom in first-run syndicated content. Increasing restrictions on advertising and educational content mandates also played a role alongside broader cultural changes.
The CW continued airing non-E/I cartoons until the 27th of September 2014. Among the Big Three traditional major networks, the final non-E/I cartoon Kim Possible aired last in 2006.