I agree that it is unrealistic for me to know what I want to study at this point, but from what I understand the school is not concerned with if I actually follow my plan. They just want to see that I can identify at least one reasonable plan of study that builds on my previous experiences. They want a few specific things mentioned so that during interviews they can ask me about my topic to gauge if I have a basic understanding of what I am signing up for. Perhaps if I was an Econ undergrad it would not be a problem, but I am an Engineer. The program would like to be sure I actually have some realistic conception of my new field of study. Everything you said about learning during the MS is true, but at application time they want a little more than "Hey! I have raw, completely naive talent"
While you might run your admissions a different way, in this case I think my adviser knows best (they have been working with this specific program for a long time).
Can anyone help me with my original question?
(I think I found a pretty good tactic since I first posted. I should try to find all the conferences on this and related ideas. If anyone could suggest a website/database that is particularly good for finding these sorts of things that would be awesome!)