The vast majority of people aren't thinking "Wow, I love how Apple takes away my freedom and forces me to use apps even if I might want to use something else", they're buying an iPhone because it's shiny and is what they're familiar with.
Those people deserve to be afforded user freedom and to own the devices they purchased.
The average user doesn't give a crap if you can sideload some random app that is only needing to be sideloaded because its likely dodgy as hell.
Also if someones using an iOS device and is skilled enough to need to sideload then they'll know full well they CAN sideload by deploying an app from xcode.
Go up to a random stranger and ask how much it would be worth to them to be able to sideload apps or have a bash terminal on their iPhone. They wouldn’t even say “zero dollars”, they would just laugh.
I am a professional iOS developer and I also couldn’t possibly care less.