What's the reasoning behind that? Because I feel the other way: for me, it's much harder to accept the idea that the Big Bang that spawned our universe was a singular event, because that would mean that there is only one inevitable end: heat death. And even though it's unlikely the human race will still be there by that time, I don't like the prospect of such a pale and bleak ending.

If, on the other hand, you assume that there was some form of time/matter before the Big Bang, there is no reason to assume that there can be (or has been) only one big bang event. And that means there might be a multitude of "universes" outside of our visible field that we can never know about. Still, it's oddly comforting to me to believe that when our universe dies from heat death, others might go still on or start a new cycle.