The advantages of coloring pages:
1) Self expression - coloring on a blank "canvas" (paper), is a method for children and adults alike to express themselves. You can inform a lot about the way a person is feeling by the images that they draw, the colors that they use, etc. It is very important to provide children an opportunity to express themselves, and not all children express themselves through words and through writing, many use art.
2) Color recognition
3) Therapy - for lots of people (myself consisted of) coloring is therapeutic. Despite whether it's doodling, or coloring the "best image ever", coloring can be a method to de-stress, after a busy early morning of school work, wind down, and cool down, after the tensions of a day at school or work.
4) Grip/Control - many children discover how to hold a pencil, pen, marker, or colored pencil, by very first learning how to hold a crayon. The little muscles needed for penmanship later on start to be developed while coloring.
6) Building motor abilities
7) Focus - Focusing on a single task for a length of time is necessary for coloring and for all sorts of things throughout one's life.
8) Boundaries - Another thing that children learn from coloring pages, with preprinted images on them, is how to accept borders. While a toddler or preschooler may doodle all over a coloring sheet, with no respect for the borders (lines on the coloring page), as the child grows older, they will start to respect those lines, and make an effort to color in between them. While I encourage blank paper coloring free of charge expression as typically as possible, for many preschoolers pre-printed coloring pages are their very first direct exposure to printed borders. This early direct exposure to borders in print, will be a huge aid when handwriting time happens, and the child has to respect the borders of the preprinted handwriting lines on the paper.
9) Turning point - This is the last little "value" of coloring that I will mention for now, and that is that coloring in the lines is a milestone, a sense of accomplishment, the initial step towards an effective academic career for many children. For many children coloring in the lines is just as important as counting to 10, counting to 100, reciting the alphabet, finding out the multiplication truths, and so forth. It's a milestone that says "yes I can" do whatever I stumble upon, and it supplies children with pride, a sense of self worth, and assists them to feel accepted in a society that is typically fast to judge, and slow to react. This sense of accomplishment will bring them through life, and assist them not to give up so easily, when something new occurs.