The fact that the prophecy 'bring balance' refers to Anakin either killing the jedi in ROTS, 'leaving the force in darkness' or killing the sith in ROTJ, leaving the force in 'light'.
In either case, if one considers the force taoist, Anakin leaves the force imbalanced - NOT balanced.
Destroying the Sith in ROTJ leaves the Force balanced according to Lucas. This is not inconsistent with the "taoist" depiction because the Force is still dualistic. The Sith are what is destroyed, not the dark side itself. As this episode goes to the trouble of showing, the dark side is a fundamental part of the Force which the Sith seek to exploit.
In the PT trilogy, Yoda kept saying how the mere existence of the sith led to the dark side clouding the force - to unbalance.
Kill the jedi in ROTS, leaving the sith in control - the force's 'dark' side increases even more, overwhelming the 'light' side.
Kill all the sith in ROTJ, leaving the jedi - the force doesn't lose its 'dark' side; this 'dark' side is merely decreased to equilibrium with the 'light' side.
So - if sith as much as exist, the dark side clouds, overwhelms the light side of the force.
Equilibrium means the jedi are dominant - only then is the force 'in balance', with dark and light sides in equilibrium - like at the end of ROTJ.
'Balance' of the force means the good guys are overwhelmingly dominant?
That's not very taoist - taoism means dark/light - opposites - equilibrium in every respect, on every plane.
In 'star wars', the balance claimed to exist on the metaphysical plane between the 'dark' and 'light' sides of the force does NOT translate to the physical realm, with only 'good' guys present.
Yes, it was like this since before this episode; the episode merely evidentiates how the candidates for fulfilling the prophecy (ROTS, ROTJ) are incompatible with a taoist force by, ironically, presenting us a taoist variant of the fulfillment of the prophecy and how different it would be.
It certainly makes the characters, both good guys and bad guys, look like foolish little critters, scampering around the galaxy and desperately trying to achieve goals they think are "correct" yet are just perpetuating imbalance. Everyone is getting nowhere fast.
However, as long as the good guys are likable, we can still root for them. Even if they understood that the Force wants the continual maintenance of balance between good and evil, a decent person is going to have a hard time accepting such a thing. I'm
supposed to let the bad guys win, even if that results in injustice and suffering, because for every bit of justice in the galaxy, there must be an equal bit of injustice? I can see why the Jedi would simply reject that notion out of hand. It's cruel and horrible.
Even if the force would want balance between 'good' and 'evil' on the physical plane (and, appatently, it doesn't, if the end of ROTJ, with jedi ascendant and 'good' triumphant, means the force is in balance on the metaphysical plane) - this balance would hardly be achieved by jedi sitting passively and letting the sith kill everyone's puppy - which would leave the universe unbalanced toward 'evil'; or by the sith just watching the jedi bringing love and rainbows - also leaving the universe imbalanced.
The balance is achieved by both the jedi and the sith fighting for their side; the 'balance' is the resultant status - an amalgam of 'good' and 'evil'.
Both the jedi and the sith must want imbalance towards their side and fight for it; but, due to the other side, all that will ever be achieved is 'equilibrium'.
If either the jedi or the sith were to only seek balance, their defeatist attitude would only cause unbalance, by giving the other, active side an advantage.
Unless there would be an accord of sorts between the jedi and the sith, both agreeing not to antagonise the other side; in essence, both agreeing to seek only 'balance'.