good point bilb.
the balance is never 'destroyed'
by killing the jedi, palps and vader take away any chance for that balance to be restored....until a jedi does the deed, that jedi being anakin in rotj.
the force was out of balance from ep1. the hints are overwhelming and redundant. the jedi are clouded and palps is taking advantage of the imbalance he created. there is balance or there is no balance