There is an animation principle called "Solid Drawing". It is an animation principle from the time of Disney's '9 Old Men'. An era before the evolution of 3D animation.
I distinctly remember an interview with one of those famous Disney animators, Milt Kahl, where he comments that animators should be able to draw well. Now, that can be a bit daunting for some animation students and these days may no longer always be the case.
But there is an important point to make here. Even if an animator says they can't draw. That doesn't mean that they are excused from drawing. A personal perception of being unable to draw doesn't mean that an animator is excused from trying to improve a skill that can be important in developing their overall animation skills. That would be folly.
The important thing to understand is that everyone can draw. We all draw our own way. An animation course is not a drawing competition. You will see some wonderful illustrators in an animation course. Sometimes being a good illustrator can be a handicap for developing animation skills. An attention to detail can be a tough habit to shake.
In the big picture, the majority of drawings an animator produces will never be seen by more than a few people. Those drawings have the primary goal to communicate ideas. The drawings are used as communication in a tribe of craftspeople who communicate visually.
As long as you can draw characters in an economical stick figure style, then you can communicate ideas and plan your animation.
Working rough, or "ruff", is the way most of the drawings are produced when planning an animation. This goes for doodling ideas for a character design, or for thumbnailing* early storyboarding, or for doing 1 minute sketches in life drawing classes. (*thumbnail size sketches)
Staying loose and sketchy captures more than the image of what is being drawn. Within loose and sketchy "ruff" line works an animator captures motion. Loose, sketchy line work illustrates forces, movement and 'the illusion of life'.
Drawing for animation is more about communication of movement through abstraction or representation of motion rather than rendering beautifully detailed images.
For the animators who illustrate beautifully already, thankyou, it is awesome to see your work. A due reward for uncountable hours, pages of all types of paper, stacks of sketchbooks, of practice copying favourite characters and evolving an own style.
For skilled illustrators drawing ruff provides excitement in drawing in a way that frees an artist up from the dedication to detail. Working ruff and not becoming emotionally invested in each drawing will help enliven your style when you return to produce a finished artwork.
Even in areas of the craft where drawing skills can be brought out on display, such as storyboarding, the same basic idea of economical drawing as communication can be applied. As Karen J Lloyd describes on her storyboarding blog, "If you’re capable of writing your name, you can draw."
In a recent post on the Animation Mentor Tips and Tricks blog, Aaron Hartline discusses the question, "Do You Need to Have a Drawing Background to Be a 3D Animator?" for animators who seek refuge in software away from the drawing board.
Just as animation has evolved from the era of Disney's 9 Old Men, when the animation principles were hatched by Frank Thomas and Ollie Johnston, so has the animation principle of "solid drawing" evolved. It has spread its intent into new animation forms, such as 3D animation, to embrace such things in as; Posing, Balance, Line of Action, Gestures, Silouhette, Meaningful Symbolism, Feeling of Weight, Implication of Mass and Volume. At the same time it is an animation principle that still retains important traditional, hand-drawn animation aspects such as Staying on Model.
Practicing the skill of drawing will make you a better animator as well as a better illustrator. Two prizes with one effort.