I'm not sure that these replies are responsive to Lucy's question, but maybe they are and they're just not responsive to the question I would have asked if I were asking. I don't think she was asking for answers to her "why" question that are essentially tautological - Why do I submit? because I'm submissive. Why am I submissive? because I enjoy submitting. I think she was asking - or I would ask - whether one ought to know what it is about oneself that makes these interactions so compelling. And I can see good answers on either side. It might be useful to know, or it might just be disturbing. Or, as some people have implied, it might be boring and irrelevant - but I don't think so.
For me, and this is pretty new, I do understand why I seek these interactions, and no, Lucy, the answer is not pretty and it's not erotic, but there you go. On the other hand, my experiences have been, for the most part, both pretty and erotic, and I'm finding that confronting where my desires stem from has not interfered with that but has made it easier to travel in a straight path to find what I need. It has also allowed me to understand why some apparently innocuous interactions are so very hard for me, and to head them off or find work-arounds rather than being overwhelmed by a sudden unexpected reaction.
I guess this is a long and incoherent way of saying that I have found that examining where these desires come from has given me more control, not less, and has allowed me to more fully embrace who and what I am.