True, analyzing past motion doesn't mean that will continue into the future. However, two things can be taken from the past motion. The first is everyone harps on trends not wobbles. If you compare data over hours or days you may be able to tell when a true change in direction is occurring versus a wobble. The second is one can compare that movement to the official forecast. Thus you can tell if the storm is tracking one way for a longer/shorter period of time than was forecast. To me, Wilma's track to the WNW instead of a NW curve(at least at this point) is significant in terms of intensity and potential landfall timing in Florida.