I know what you mean, but I maintain that if you know how to draw something freehand, it's relatively easy to draw it with a mouse, if you use a program with a variable line tool instead of just a standard pencil tool. Like Paint.net
It takes me about 20 seconds to draw an eye that I have drawn before using a mouse, and about another minute to colour it. I can then edit the colours and shape in real-time, unlike with a piece of paper where I would have to start from scratch or erase part of the drawing.