Does there really have to be a "why" for the universe? Even if you'd like to believe there is, I don't believe there is any way to figure it out. The reason we have science in the first place is to explain things as best we can, and even that is far from perfect. The universe really is as cold as science seems in explaining it.
Also, if you actually believe in eternal recurrence, notice that this concept, if it were true, would still only explain things in the way that science does; that is, it only describes an observable trend, it doesn't say anything about why it happens.