There is no artist, who would buy their children coloring books or taught to paint pictures. What does this mean? Coloring is a kind of framework, hindering the development of the imagination. They contribute to the formation of habits of the finished drawing, in which a flight of fantasy and free creativity is almost impossible.
"The golden age" of coloring books is believed to be 1960-s, because almost all characters were depicted in them, as well as some products (like Planter Peanuts or Campbell Soup)