The con of making something a symbol is that you can't move individual points for a single instance of the symbol, i.e., if a point is moved it is moved in all instances. Another con is that certain transformations are not possible like perspective. The pro is that swf file size is much smaller depending upon the number of frames the shape appears in. If a shape is stationary, there is no advantage in it being a symbol. I am going to simplify this situation in a future version by having shapes that are drawn be symbols by default (unless stated otherwise in preferences). Maybe attempting a point operation on a symbol will ask the user if he wants to make it a non-symbol.