I've been looking for a practical use in applied science for the information that all life on earth evolved from a microbe that existed billions of years ago, but can't find any. It seems to me that the whole Universal Common Ancestor thing is completely irrelevant and useless outside the realm of evolutionary theory.
I would argue that as we go back in time, any historical event becomes increasing irrelevant to modern times. But it still is information on how things are thought to have become what they are today.
Is there anything relevant and useful in knowing who your grandparents were, say 40 generations back?