I almost agree with you ...
But the Dark Side is fueled by fear. Fear, anger, hate, because it's driven by selfish emotions. And as said in Episode III (as if any of us didn't already know this) fear of losing one's power, that's top on the Sith list. They only appear to be fearless because they don't care about hurting others if it gets them what they want.
The theory of one can't exist without the other, I somewhat agree with. After all, is the existence of light even known when there is no darkness? Shine a flashlight during the day and it's practically invisible. Shine it in a shadowy place and it captures your attention. However, though the Jedi did slowly die out from the times of The Old Republic until the crest of the Rebellion, once the Rebels had won the war the Jedi started increasing in numbers once more, and continued to increase, to the point that an Academy was formed. That's not to say that no Sith existed though, obviously.
Lol, more nerd logic
I seriously need to dig out my Ultimate Guide to the Force.
Anyway, for the most part ... in regards to the Star Wars universe I do agree with the color descriptions. But then to throw a monkey wrench into the whole thing, when Luke did finally build his lightsaber it was green