Must think about this a while before fully answering, BUT ... I think that ee's comment is exactly where there's the most vigorous debate, in a lot of dance forms other than just competitive ballroom. (Several difference swing dances and AT come to mind.) There are the purists who think that, at some point in time, the dance reached its peak and should remain in the form, frozen in time. Then you have the proponents of evolution.
It's amazing how passionate people can be on either side of the argument.