Thanks. I've always found some lines of thought on this subject strange. Another one is why God would want to wait so long ... as if a being, supposedly outside time, waits for anything.
First off, this isn't a creation vs evolution debate. This is specifically about theistic evolution. To those who believe in it: do you find it bizarre that god would create a unicellular organism and then allow it, through various mutations, to evolve over billions of years? Why would an almighty god go through so much trouble, especially when creating beings out of thin air is a much simpler process?
I don't believe the question is "Why did God do it this way" so much as "How did God Create this Creation". Because we are now able to "see" the ongoing creating process of this Creation through the sciences, we know that part of the "How" is that it did take billions of years and is in fact still ongoing. As for the "Why" that you ask about...I don't know the mind of God, so I can't answer that one.