Way before we had videos, computers etc there needed to be a way to remind yourself of the great many moves that can be used for self defence, writing them down isn't useful as anyone who has tried to teach themselves something physical from a book will tell you so kata was 'born'. A way of keeping all the self defence moves in one 'bundle' so you could learn them, remember them and use them in a way that is also aesthetically pleasing but also keeps you moving in the correct manner. Too many people have taught kata without the Bunkai losing the purpose and meaning of the kata leading to people saying well you don't fight like that! No, you don't but it's the individual uses of the individual moves within the kata that are important.
When teaching boxing trainers can use a very simple kata to teach the punches, 'jab, cross, uppercut' you don't necessarily use them in that order or all three in a sequence in a boxing fight but you have all three in your armoury through practice, you go on to learn combinations etc but that's your basis a very simple 'kata' to learn, remember and refine your punches.
When teaching boxing trainers can use a very simple kata to teach the punches, 'jab, cross, uppercut' you don't necessarily use them in that order or all three in a sequence in a boxing fight but you have all three in your armoury through practice, you go on to learn combinations etc but that's your basis a very simple 'kata' to learn, remember and refine your punches.