First of all, absolute necessity doesn't exist. We only need food and water in order to stay alive. There is no imperative that we need to stay alive. There is no, indeed, absolute imperative anywhere governing the action of a self. If there are absolute imperatives, they operate at a scale higher than that of an individual ego. As such, we don't NEED food and water. Plus, utter un-attachment to the world includes those things that exist in the world. Specifically, food and water exist in the world. Are you saying that achieve enlightenment we must detach ourselves from food and water? Gautama Buddha would disagree: he even said so to the ascetics.
I further disagree with the thesis that complete un-attachment to the world is the only path to enlightenment, because I don't believe that there is a single path to enlightenment. We each have our own Dharma, and that is our path, our Way. Enlightenment can be attained through a complete lack of attachment to the material world, or it can be achieved through a complete immersion into the material world, and an infinite number of other ways.
To claim that there is one Way is to make the same mistake that plagues the Abrahamic faiths and has led to war, death, and unrest throughout history. In striving for truth, we must recognize that there are ten thousand ways to come to truth, and no named Dharma has monopoly on access to that truth. We start on our paths towards enlightenment before we are aware of it, and once we begin actively seeking that end, we have already set our selves into certain modes of operation, and these pre-conditionings make it so that we are closer to the truth by one path than another.
My Dharma is not your Dharma. But my Dharma leads me to the same joy and understanding to which your Dharma leads.