Properties of the New Inflationary Scenario of the Big Bang could explain the common observation that this universe is "ideally" suited for us.
As the NIS envisions creation of almost infinite (if not absolutely infinite) universes, there can easily be many "failed" models or versions which don't support our kind of life--in fact if there are an infinite number of them, by definition there are an infinite number of them that are unsuited--and an equally infinite (i'm not making this up!) version that could be perfect for human life.
If there are not an infinite number, but merely a very, very, very large number of alternate universes, there will still be a subset [of some number] that support human life due to the very, very, very large number of total possibilities.
The fact that ours happens to be "the one" or "one of the few" is merely an extension of the anthropic principle, to wit: if this universe was unfit to support human life, we wouldn't be here to ask the question.
I would further argue that I'm not sure this one is so "perfectly" suited for us. I, for one, would prefer one that didn't inherently cause cancer.
wr/Geno