I feel that the whole set up, with the Dark One and Pattern at least, is an artificial construct put on by the Creator, to allow all possible aspects to be present, without the Creator's own demise.
I guess I like to think that the world itself and the people / souls within it can continue on without the three, but the presence of only the Dark One or the Creator would unbalance it, so both need to be removed, and with them the reason for the Pattern to be there.
Only the Dark One is Evil, not just "the source of", but is, as the book said, kill it and you get a one way trip to a world that would give a care bear cavities, it's "will", maybe even "power" is imprisoned, but it "essence" is a part of everything.
One can only assume that the Creator is the same for "goodness"..... What with "The Light" and all(much like "The One Power" it took me forever to get what they meant when they said that...).
And as for the Pattern..... Well, for one I assume you mean the "Wheel", as the "Pattern" is what is woven by the Wheel, and... Is basically just another word for "all existence", destroy that, and well.... Everyone would be dead at that point, as they'd no longer have anywhere to not be dead in.
