I do not work very often with Flash CS these days, but those occations when I do I mostly use it for creating and deploying banners. Often its more than one banner that needs to be done, in different formats and sizes, and in almost all cases you create one original file that you later use as a base when doing the different sizes.
This little feature would help speeding up the process a little (so you do not have to alter the export .swf name settings everytime you create a new base banner from a original). The variable width/height would represent the .fla width/height.
This feature would help you keeping track of your banners, and will shrink the amount of errors in your deliveries, less "wrong size" named files (all you people in the banner factory knows what I am talking about!).
Adobe, can I have it, please? :)