Pants are inefficient
Everything else has been tweaked to make things easier. But taking a shit is still difficult, because you have to pull your pants all the way down. You have to undo the belt, unzip or unbutton the fly, and then lower those things, which can be a nightmare for people in a wet-floored bathroom stall or for people who wear skinny jeans (I assume).
Just as there’s a way to take your dick out of your underwear while pissing, we need a way to make this happen for shitting.
I don’t know how to go about inventing this; I’m no pantologist.
So get on this, fashion designers. Stop doing coke and imagining models walking down runways in tin can shoes and do something productive.