I doubt they'd even get the RND cost for that change back, this is a feature no one cares about except a very very small minority within a small minority. I'm a hardcare FOSS only user and only use grapheneos/fedora linux on my devices for privacy and security reasons and even I am not remotely concerned about hardware switches when i can just powerdown the wifi/Gps/wwan connection.
At the moment iPhones seem to drain power even when they are "off" which makes me suspect that they aren't, in fact, actually fully powered off. There have been a few occasions when I have been without a charger for one reason or another, and would like to be able to fully power off my phone in order to save battery.