Our goal mechanically is to reduce the amount of stress to the "system".  The system consists of teeth, gums, bone, muscles, jaw joint (TMJ), nerves, etc.  When one has a "balance" between the favorite position of the jaw joint (TMJ) and how the teeth bite together, this creates the most stress-free position.  If we provide this balance between the meshing of the teeth and the jaw joint (TMJ), one of the two causes of dental disease (plaque and stress) is controlled.  Think of a gate in a fence.  The gate swings on the hinges (TMJ) and the latch (teeth) engage to lock the gate.  When the gate works normally, the gate will swing smoothly closed as the latch smoothly engages.  What a well balanced gate one might say.  The jaw is the same idea.  When the jaw joint (TMJ) hinges as the jaw closes, the teeth mesh together (like the latch).  If the balance is there, the teeth come together smoothly allowing the TMJ to also work smoothly.  If the gate is not balanced, the latch will not engage unless you lift up on the gate to line up the latch.  This lifting up creates stress on the hinges and they wear out, get loose, get noisy, etc.  The TMJ (jaw joint) is the hinge and if the teeth do not engage, the TMJ must shift around to allow the teeth to engage.  Just like the hinges on the gate, the TMJ will wear out, get sore, get loose, make noises, etc.  One can see how the mechanics can cause undue stress.  The stress will attack the weak link in the person.  Everybody responds differently.  It behooves us to minimize, or eliminate the stress so parts of "our system" will not break down.  Balancing the bite is a form of prevention just as brushing and flossing.