Most children love watching cartoons. Needless to say, cartoons do not have realistic pictures or photographs but most often characters with exaggerated features. Many look silly in fact but kids love them. Silliness and simplicity of the illustration style appeals to them.
Any child who draws a picture is not going to be able to make a realistic picture. At the most the drawing might have some resemblance to reality but nothing more. To be able to see a story weaved around simple drawings with exaggerated features that are kind of similar to the pictures they can draw, kids are on board. You have got their attention.
Children have very imaginative minds. They relate to abstract pictures as long as it has some resemblance to reality. For instance, a tree would be anything that stands with a bark and a shape on top.
Pictures speak more than words
At times the pictures do the talking more than the text. Too much of realism in pictures leaves little room for any imagination hence letting only the text to do the talking. That is boring for any child who is less than 8-9 years old.
Most children’s books shy away from realism as it steals the depth from a story. It takes away the need to revisit the same storybook several times with the desire to experience something new or just enjoy the story for what it is, based on pictures that speak volumes, even though they are simple.
Observing pictures and visualising meanings of words
Drawings/illustrations enhance the story and the emotions. The context provided by them motivates children to go back to the story book again and again, to see if they notice anything new or relate to the text better by simply observing what the pictures are trying to tell. This is the first step to independent reading. Visualising what words mean in terms of pictures enables children to remember the story better and enjoy it more, each time they are read to.