With online printable coloring pages you never have to keep volumes of coloring books around. Most children change what they would like to color often. They bounce around from one theme or one set of characters to the next. Therefore they may abandon that coloring book with princesses or cars days after you buy it. Printing out the pages though allows them to always get what they want.
Coloring books are a thing of the past. Kids today aren't as thrilled by a basic coloring book as children a generation ago. That is because these children have been spoiled by all the fantastic new methods of coloring using the computer or with fancy markers and pens. While you might get away with a coloring book and crayons for a long car trip, don't expect your school age children to sit quietly at the table coloring pictures the old fashioned way - there is a something better around, and they know it.