There is a big difference between "We don't know." and "godditit". One is what leads the scientific process on to new knowledge. The other has, for all of history, stopped the developement of new knowledge.
Exactly... The desire to know ultimate causes shouldn't paralyse the continued quest for progressively deeper knowledge.
I once came up with a nice (I think ;-) ) one-liner for this:
"For a real scientist, 'God' can only be the answer to the question(s) that lie directly behind the current question she's trying to answer."
That's basically the only way to keep the machine running...