It's extremely important.
EDIT: Sports, athletics is essentially a collection of physical movements. If a sports game want to replicate the sport, physical motion must be done properly. That's why they use motion capture tech. Madden's "walk cycle" and "standing pose" does not resemble real motion. It's also not an efficient way to walk or stand. It's extremely taxing on the quadriceps and other muscle groups.
I'm not an animator but I've read a bit. In the world of animation, after all the other exercises such as the bouncing ball, squash and stretch techniques, overlaps, follow through, weight shift, etc..... you must know how to do a proper "walk cycle" and "run cycle."
Frankly, what Madden's current "walk cycle" exhibits would never ever pass in the eyes of any amateur animator let alone any professional animator.
It's the basic foundation for movement. The ability to animate athletic movement helps separate you from regular animators.
Here's a list on another message board that bullet point exercises that any animator should be able to grasp.
http://www.11secondclub.com/forum/viewtopic.php?id=4773