Why is it so acceptable that 'God' did it? That He is the creator and originator of existence? Why does one 'not' wonder where did God come from? Who created Him? Who does He worship?
If one thing is true of all creation and all existence is that things don't start off already complex. They evolve from a simple state to something more advanced.
The journey to eternity is a long one. I think both theist and non-theist have the same dilemma; how did it all get started?
The theist would question the Big Bang because it doesn't answer their spiritual question of creation. Yet, the answer of, 'God' is just as lacking.
Excuses are tools of the incompetent used to build monuments of nothingness. Those who use them seldom amount to anything.