Even if determinism has a worldly cause, like physics, I don't see that it means anything. It's a different context. Thought and choice and pain don't exist on the level of atoms and sub-atomic particles, and that's the realm where determinism would exist. Choice is a human-level abstraction, maybe, but it's what has meaning when dealing with morality. Even if choice is an illusion, that illusion is what matters in the context of moral decisions.
Think of cybernetic physicallism. Imagine we are just a series of electirc pulsions and chemical reactions, and our thought or reason is based only on that, making us like complex PCs with no choice whatsoever over our actions. Now suppose we KNEW this, not that we suspected it (Like many do now) but that there was actually evidence to proove it. This would instantly give human beings the value of machines, which sucks, but it would also keep them from any blame for any action, since they had no choice.

Yeah, I don't like determinists.