NERD ALERT: In Star Wars, how is the concept of wiping away all traces of the dark side, considered "balance"?

The Jedi Council continually remarks on “the one who will bring balance to the force”. However, it would appear that by that, they mean completely repressing and even destroying all those who know the ways of, or would use, the dark side of the force.

Let me paint a picture for you here: Think of a classic scale. On one side you have the light side, on the other you have the dark side. Now completely remove the dark side and what happens? HOW is that “balance”?