Most Bluetooth headphones are encrypted with a key shared only by the headphones and the host device. Not sure why you think they aren't private. Maybe really cheap or really old headphones might not be so secure, but the vast majority of Bluetooth headphones in use today absolutely are.
Charging and audio quality are legitimate concerns, but again, you still have a headphone port... It's just part of the USB-C port on the bottom of your phone. A $5 adapter completely absolves you of having to use Bluetooth.
I really don't see how needing an adapter is a big enough deal to care about the way people here seem to.