Exactly, and it's Lucas own explanation in interviews: Anakin brought balance back to the Force by his self-sacrifice and finishing off Sidious. He did it for Luke (and through him, for Padmé and Leia), and because Luke chose to die rather than embrace the dark side, wouldn't do it to save those he loved. Luke reminded Anakin again what selfless love really was.

The concept is eastern (but not taoist, which isn't about good and evil, it's rather mostly Zoroastrian where evil is like a virus that humans musn't make grow by avoiding evil/sins. In the face of evil humans must act like "antibodies". That taoist aspect in Star Wars is limited to Luke and Leia/Padmé and Anakin). Balance means cosmic harmony, it has no relation to the western imagery of balance scales, or with numbers. Evil exists, but it must be rejected, and thus are the behaviors leading to evil, like greed and possession.

The rise of users of the dark side to take control of the galaxy threw off cosmic harmony complelety. Anakin rejected the dark side and sacrificed himself to destroy Sidious, thus no Sith remained and the Force returned to its cosmic harmony.

The death of the Jedi have nothing to do with it, their selfless use of the Force and rejection of the dark side doesn't break cosmic harmony. It's the Sith philosophy and use of the dark side that breaks balance. The Jedi died because they failed to stop Palpatine before the dark side was so strong only Anakin could still destroy him... and decided instead to join him. The Jedi Order became collateral damages of the destruction of balance in the Force.