Security ... think about it!
Some people have suggested that forms were designed originally for the purpose of passing down fighting techniques secretly, negating the need to document them and thus risk having them being exposed or stolen. While others suggest their designed and sole purpose was to provide a pre-determined set of training aids to improve such attributes as balance, coordination and timing, just as we might see a Western boxer using his shadow boxing. There is probably some truth to both, and this would explain why some forms flow naturally into successive techniques whilst some others are a combination of techniques which don’t seem to flow together.