Its interesting to think about the way that omission relates to personal responsibility. Essentially it outlines a set of behaviors that all people are expected to engage in almost without qualification. On a more basic level, it requires us to help one another, to act unselfishly and to consider the role of the individual in a communal society.
I would like to see a list of all the different behaviors or circumstances in which the legal definition of omission has been applied. Surely they are a lot and there is probably a lot of contention as to where the boundary falls. I bet there is a legal scholar somewhere out there that focuses on this issue alone.