Not 100% sure if this is what OP was refuting to, but it is on F-Droid using the IzzyOnDroid repo.

https://f-droid.org/packages/com.hjiangsu.thunder/

My very simple guess is this. It requires more parts, bigger assembly line, overall higher complexity, adds weight, makes the headset more fragile, and so forth, so I’m sure if they can make a design that accommodates the majority of users, it is cheaper to say “good enough” then to design and accommodate for the rest of the potential users