The KJV doesn't really translate the last part of this verse as much as try to communicate its general meaning without translating it. The NIV ignores many of the words of this verse because, obviously, Jesus was just rambling on for no reason and no one today really cares.
Remember, this parable started making this king, not the wedding, an analogy for the realm of the skies. The story thus far has the king invite some to his son's wedding, those invited refusing, killing the messengers, getting killed in return, now inviting everyone, the "good" and "bad." The terms used for "good" and "bad" are closer in meaning the way Jesus uses these words to "valuable" and "worthless." So the wedding is filled with many people who didn't start off as valuable, but they are being rewarded just for coming to the celebration. But the story doesn't end there.
Christ's Words in Matthew as a Guide to 40 Days of Prayer.