I mean, things could be that way. It's not so hard to imagine a universe where some events just happen without any causation or correlation with past events. The astonishing thing is that there is any causation at all! That events at different times are related to each other.
You think a billiard ball that just starts moving for reasons of randomness is less astonishing than a billiard ball that moves because it was struck by another ball?
Of course we are already used to things being that way.
But a priori, order is what needs explanation, not orderlessness.
The interesting thing is that there is movement. That there is temporal structure. It's not like one instant is totally different from the previous. And that there are simple laws governing how the previous snapshot relates to the next snapshot.
Why isn't the universe simply white noise, like when you tune on a non-existent channel on old TV's and you get totally independent, random images at each instant.
What's the alternative? That something happens without a cause?