What I really like about the beginning of samsara being unknown or even unknowable is how it challenges the Western concepts of what constitutes a religion and what we can hope for when turining to spiritual life. In fact, it is a feature that distinguishes Buddhism from so many not explicitly religious currents in the Western thought like different metaphysical theories or the contemporary cosmology as well.
What does a typical adherent of a monotheistic religion or a so-called ‘secular’ Westerner with a scientific and naturalistic view of the world think about the absolute true knowledge of the origin of the world? Or, as you may re-formulate this question after a little bit of pondering, what is one of his or her deepest yearnings that he or she seeks to satisfy with religion? I think it can quite possibly be his or her wish for the world to be a coherent narrative, with a distinct beginning, middle and end.
It doesn’t really mater what the beginning may look like: ‘God created the Heauen and the Earthe’ or ‘Beginningless Samsara’ (not ‘with unknown beginning’). It doesn’t really matter whether we will be able to grasp the overarching story in this very life. It can be either achieved by future generations of scientists and / or philosophers if we are talking about naturalistically thinking ‘secularists’, or God like some cosmic Hercule Poirot will explain everything to us after we die. It doesn’t matter because what matters is that such a narrative does exist in the eyes of a believer. If there is such a narrative there is some possibility of control, of opposing the anicca of existence and escaping dukkha without abandoning the oh so dear self. Hence endless eschatological ruminations in Abrahamic religions, detailed descriptions of heavens and hells in Indian religions and popularity of absurd religions like Scientology and Mormonism: they are absurd, but they are selling you such a good story…
What the Buddha does, or at least what the Canonical Buddha does instead is pointing out how pointless this belief in an overarching narrative is, and indeed how pointless it is trying to find it. Not that there is no Absolute Truth or Ultimate Knowledge about how the things really work - there is still, you know, Buddhadhamma - it’s just that it is very much possible you will never ever find out what it is. It is possible nobody will ever find out. So stop looking into the foggy landscape of past cosmic aeons and just start meditating, for Bhagavan’s sake!