I can't honestly tell you the last time I DIDN'T use the ignition switch to turn off a motorcycle. Why would a person use the kill switch? None of my street cars or trucks have a kill switch.
Normally because the kill/emergency/engine off switch is conveniently thumb operated, and a hand doesn't need to be removed from front brake actuation to turn off the ignition. At least that's what I have read in countless forum posts from many different model owners. Kill switch usage, yay or nay, seems to be a hot topic on most all motorcycle forums, for some reason.
I use the Kill switch, then turn off the ignition, by locking the forks, then place the kill switch back to the 'on' position, so I won't wonder why the damn thing won't start with the next use.
Personally, I liked the way my old dirt bikes worked. Give it a kick, it started. To kill the engine press the button on the handle bars with left thumb. Rinnnnnggg ding ding ding, da dinnnnnnnngggg...