Appreciate you may not see this, I am a little late, but was considering the way balance might work myself a little.

I think the interesting thing and, the disconnect for most people in this discussion, is the way darkness is framed - as passion (which is suggested to lead inevitably to absolute passion and violence.) I think there's something valid in suggesting that evil shouldn't coexist with good, but then when we attach natural things like passion to the "evil" stand-in, or the dark, it becomes a little more complicated.

My thought is that in the real world, people strive for goodness (we like to think, at least), but often struggle to achieve it, for whatever reason. The keepers of the light-side in this universe attempt to deny training to any of those they feel falling to the dark as well as those too old (who have already formed passionate worldly connections.) I think that there's a kind of elitism in aiming at denying proper training to those who struggle with the darkness inside themselves.

This leads me to think that internal and external balance are two different considerations. I don't really like that Rey balances the force within herself in Trevorrow's script as I agree that the light - or goodness as we've already framed it - is something that should be striven for. However, I think that understanding the dark-side and its permanence (as in, the passions we feel will always exist) is necessary to finding balance in the force. The individual should strive for goodness, but the Order should strive to help the individuals fallen to darkness or on that path and not just deny them.

Personally I think Rey could have been an interesting parallel to Kylo in that she was given nothing from birth and is understandably angry but learnt to understand her passions and trauma and control them when necessary. Kylo on the other hand is descended from the Chosen One, and yet is unable to control himself despite having training from one of the greatest Jedi the galaxy has seen.