A person standing on two feet is an unstable structure.
There is no such thing as balanced movement. There is only unbalanced movement. The feeling of balance is the result of an unconscious process in which we are constantly readjusting. Fear of falling causes us to develop foot and leg muscles which are constantly at work to keep us feeling balanced. What most people call "rooting" in martial arts is simply a continuation of this process.
One of the reasons the higher levels of martial arts are so hard to achieve is because we are afraid to give up this unconscious reliance on our legs for balance.
Toddlers balance by moving their torsos while their legs remain soft and springy. In Taijiquan we say, "Move from the tantian," but most people use their leg muscles for balance and power which limits the expression of the tantian. To achieve the higher levels of martial arts the legs must be part of the movement of the "tantian," not a separate force. If toddlers can do it, so can you!
The way I learned Baguazhang, I was told to always be "on balance," and to always be able to "turn on a dime." Thus forward motion was propelled by twisting and pulsing the legs. There is a Yin style Baguazhang school in San Francisco that teaches the opposite. They teach that one should always be leaning so that one's spirals will be driven by the momentum of falling. Both these ideas are missing the mark.