* The rise of new forms of entertainment. In the 1950s and 1960s, television became increasingly popular, and this led to a decline in the popularity of movie theaters. This meant that there was less demand for animated cartoons, which were typically shown in theaters.
* Changes in animation style. In the 1950s and 1960s, there was a shift in animation style from traditional 2D animation to 3D animation. This change was driven by the development of new technologies, such as computer animation. 3D animation allowed for more realistic and detailed images, and it quickly became the dominant style of animation.
* The rise of children's television. In the 1970s and 1980s, there was a boom in children's television programming. This led to the creation of many new animated series, such as "Scooby Doo," "The Smurfs," and "He-Man and the Masters of the Universe." These new series were more in line with the tastes of contemporary children, and they quickly became more popular than the old cartoons.
As a result of these factors, the old cartoons like Felix the Cat and Top Deputy Dog Wally Gator have become less popular. However, they are still available on DVD and streaming services, and they can still be enjoyed by fans of classic animation.