My guess is that since MK uses Front P/K and Back P/K (As opposed to stand Light and Heavy), the plan was to maybe make it more realistic and in depth so that may your combos or reach of them would differ based on your positioning (if front kick is with your left leg, then maybe in a stance switch, its with your right leg). The thing is, MK is a game of setups anyway so we're going to play footsies, zone, punish and go to BnB's and options from there on out instead of stance switching just to stretch the hitbox out a neglible amount. Only thing left I wonder is that has anyone tried maybe seeing if you can use stance switch to cancel stuff? I feel like that button is a remnant of the Armageddon/DA/MK vs DC era where stance switches maybe changed styles or something (I'm ignorant, stopped playing MK after 4, correct me if i'm wrong)
I say they should take a page from IGAU's book and change that button to a dedicated MB button.