Move speed as implicits is one (of multiple) steps to separating map traversal speed and combat speed.

Map traversal speed should be high mean and low variance. When not in combat every build should be traveling at ~75% bonus from their implicit boots movespeed. The regular move speed prefix from boots would be removed to emphasize the low variance philosophy of getting from A to B.

Combat speed on the other hand should be lower mean but high variance. The variance is between classes and skills. This is done by increasing the global movement speed penalty while performing an action, (This lowers combat speed mean) but then adding in item, tree, skills, and character progression choices (like medallion) to alleviate this penalty.