I don't need unscripted sparring to develop timing.
I don't need unscripted sparring to develop speed.
I don't need unscripted sparring to develop power.
I don't need unscripted sparring to develop technique.
I don't need unscripted sparring to develop confidence.
I don't need unscripted sparring to develop mental toughness.
I don't need unscripted sparring to develop aggressiveness.
and on and on.
So.....why do I need unscripted sparring again?
Think of it like a tennis player.
Sure, I don't need to practice against a live player to develop timing. I can hit balls launched at me by the ball machine.
Sure, I don't need to practice against a live player to develop speed. I can do all sorts of speed drills.
Sure, I don't need to practice against a live player to develop power. I can lift weights.
Sure, I don't need to practice against a live player to develop technique. I can work on one technique at a time against a ball machine.
Sure, I don't need to practice against a live player to develop confidence. I can keep hitting back those balls launched at me by the ball machine and be confident in my techniques under these circumstances.
Sure, I don't need to practice against a live player to develop mental toughness. As long as I only play against the ball machine, nobody can question my toughness.
Sure, I don't need to practice against a live player to develop aggressiveness. I can crank up the speed on the ball machine!
So....why do I need unscripted sparring again?
Because, no amount of preparation against the ball machine is going to replace the unpredictability that is inherent in a live opponent. Live opponents can hit shots with topspin, underspin, or flat. They can change pace at a whim, without having to turn a dial or punch a button on a machine. They can hit the ball to where you are not, which the machine will probably not be able to do. The live opponents can act and react, and even establish an overwhelming presence on the tennis court, whereas a ball machine is still a ball machine...
The exact same thing can be said about sparring. While you can certainly practice techniques in a pre-arranged pattern, such as in ippon kumite, in the end, no amount of ippon kumite training will substitute for going against the unpredictability of a live opponent.