How about because you don't want to take a step forward.When you kick, if your
- kick land on your opponent's body, you want your kicking power to go deeply into his body.
- opponent catches your kicking leg, you want to shift weight on your leading leg so it can be hard for him to hold on your leg.
- opponent steps back, you want to land your kicking foot forward to gain the distance.
I can find 3 reasons not to retract the kick. What's the reason to retract the kick?