These VAM Vega/Factory drop rods or as often called extension or down rods are important as they bring the ceiling fan down to the correct height for the correct and most efficient operation which is about a meter above head height.
If your ceiling is above 2.8m/9.2ft then the length of drop rod that needs to be added will be whatever is needed to keep the fan at a 2.8m/9.2ft height. The wires carrying power and control signals to the fan are threaded within the drop rod so beware that they will need extending if you use a drop rod longer than 24″.
If the fan blades are properly balanced then there should be no wobble even with a long drop rod.
Note that in certain cases a ceiling fan will require a thread at both ends of the drop rod. This will be specified in the fan description.