I think Kishi didn't want it because it would be bad match up for Sasori.
Sharingan detect his only organ using chakra and he would kamui his little heart.
yeah this is a possible way for victory, but come on. you think sasori would lose to kakashi? that was early part one so a kamui would take a long time. and he was not skilled at hitting moving targets
if sakura can dodge it i say kakashi can dodged those things without effort. and sharingan can detect chakra so he would railiri his core and sassori isnt that fast
I think Kishi didn't want it because it would be bad match up for Sasori.
Sharingan detect his only organ using chakra and he would kamui his little heart.
Sakura managed to dodge it because she was manipulated by Chiyo so don't come with that bs.
OT: Early part 2 Kakashi would have gotten destroyed by Sasori, however since plot would have been on Kakashi's side, Sasori would have most likely lost.