Just for fun, on what document, quote, theory do you rest the idea that God is perfect?
And if God is/was perfect, why would there be the need for anything else? (What motivated God? A lacking? A desire?) It would seem reasonable to assume that ALL (God) was not perfect until he "let there be light" etc.
In which case, I've got some funny hunches about the perfection (God) the universe(s) are completing....
Basically, God is (re)creating himself through reality, like a smoke-ring twisting around itself as it moves into the future.
Maybe "reality" is the only way God can "travel".
I'm no Biblical scholar (and am not now nor have ever been associated w/ a conspiracy--ignorant or otherwise) but I think Holy Scripture presents God as a perfect being.
Just for fun let's look at Milton's answer to your question, ie, why bother w/ creation if He were indeed complete.
In Paradise Lost JM posits that w/ the fall of Satan, God created man to redeem perfection. When man was tricked by Satan, Jesus Christ was sent to earth to redeem man (sorry, a bad synopsis). In the fullness of time JC will return and Paradise (along w/ us) will be regained.
IOW Creation is the process God works through to maintain perfection. Not entirely different from your smoke rings but w/ a point. Obviously the point is probably far from the mark, but I think worthy of consideration. (Milton's point-not mine).