The idea is an answer to the Question of Evil: i.e., why does stuff suck? If whoever created the universe is benevolent, why do bad things happen? Why is Creation imperfect?
And the answer is: because it's not finished yet. Creation is still happening; evolution, civilization, scientific progress, all these things are part of God's ongoing creation of the universe.
I like this idea because not only does it answer a tough problem, it also tells you what to do about it. If the universe isn't finished, then as self-aware parts of the universe, clearly our job is to help finish it. The point of existence is to make things better than they were.
Do I actually believe in this idea? Sometimes. Ask me later, when we're done...