What are we supposed to do with it and why?
I believe that all concepts can be tested within the Epicurean worldview. In the sense that one can sometimes try to take a concept and adapt it to one's own purpose. In this particular case, I believe that the very idea of a dichotomy of control is useless in the pursuit of pleasure because it leads to the recognition of the superiority of reason over the body. Categorizing desires is much more sensible. Because categorizing desires directs us to reflect on desires in terms of their achievability, leaving much room for flexibility. It seems to me that this criticism may be useful in discussions with uneducated Stoics, because such Stoics often actually strive for mental peace, and not necessarily for what the ancients called "virtue". These Stoics often treat as sacred this principle of dividing dependent and independent things.