I've had two battery replacements since 2015. One of them was required, the other was mostly optional (battery had dropped to 90% on my iPhone - which was probably sufficient).
USB-C - that was an awesome requirement that it was unclear whether Apple was ever going to do.
User Replaceable Battery? Zero desire, particularly if it reduces water resistance on the device. Dozens of things I've wanted from a phone - being able to replace the battery has never even entered my mind as something I wanted.