It offers a lot more features than does, say, MS Paint. It also offers an interface designed to be so simple even a literally illiterate child can use it with ease.
I am always grateful to people who design and make available programs to download such as this one:
http://www.cs.uu.nl/~markov/kids/draw.html
So I sent a note of thanks, and then began to draw buildings and fireworks. Also, guppies.