Hmmmm... I'm not sure where people got the idea that locomotion is new or some kind of an engine all to itself to be compared to a physics-based engine. Locomotion is just standard animation terminology describing the operation of the parts of an animation cycle and/or behavior, its variations, its blending, etc. Even games featuring physics-based engines include locomotion. You've been witnessing locomotion in practically every game you've ever played. Sometimes it's done well, sometimes it's not. Here is a visual demonstration of what locomotion means in action:
http://www.moddb.com/games/epsylon/v...omotion-system
When you run, back up, block... it's all part of a cycle of animation frames adhering to a behavior until another event, condition or action causes the model to do something else. The only advantage we've seen a physics-based system make for football is in the collisions, but the rest of the animations you've been seeing are mo-capped in the standard way just like every other football game, because they have to be (unless you exclusively keyframe, which would be a disaster).
The collisions in Madden need serious help, and physics-based collisions would certainly do the trick, but it's not going to eliminate any of the core issues with the game beyond the superficial.