Sure, I always read an epigraph in a chapter or book or poem when I see it. It's part of what the author chose to provide us with, so the author presumably had a reason. Although granted, as you said, the author's reasoning in putting it there isn't always obvious.
I've written an (unpublished) novel that uses haiku for epigraphs at the beginning of each chapter. The story is about people traveling, so it's actually supposed to be a kind of haibun.