I have a couple responses regarding complex machines and responsibility. Firstly, as to whether or not we are complex machines, the fact that you don't want to think of yourself as a black box or a very complex machine is somewhat tangential to the issue. If we both agree that there is some sort of objective reality outside of ourselves than either we are complex machines (materialism) or not (dualism? please forgive me if I am putting words in your mouth) and the way we feel about it does not change that fact (whatever it actually is). My point here is just to be cautious about accepting or rejecting a hypothesis just because of the way it feels.

But as for responsibility, even if we were to suppose that we were "merely" complex machines, I see no reason why we cannot still be pragmatic and assign responsibility based on the ways people act, and what their states were that led up to their actions. Contemplating root causes beyond that level is problematic no matter how you view the universe--is there a devil that causes one to sin or does it depend on the initial state of the universe?

In my personal opinion, the only domains that materialism remains poor at explaining are free will and qualia. For free will I can hand-wave and assert that free will is an illusion which our brain provides us with because it has some sort of evolutionary advantage, perhaps in helping us decipher when actions arise from within the individual or from within the environment. For qualia I yet have no explanation. :)