Epiphenomenalists are well aware that phenomenal consciousness, as they understand it, plays no causal role in the world. This is indeed obvious. What's not obvious is that it's a fatal "flaw" in their view.

On the contrary, anyone can quickly note that 'epiphenomena' cannot be responsible for any aspect of the universe's behavior, whether they're ones we're aware of and capable of measuring or completely unknown to us. That means that we have no way of gathering information about them, and that as far as this universe is concerned, there are no consequences of asserting their existence that differ from exerting their nonexistence: the concepts are identical.

Perhaps it really isn't obvious to you why that's fatal.

I'm afraid, though, that codifying incompetence and calling it a disciplinary branch is not enough to validate it.