Wireless headphones necessarily have to include rechargable batteries, which are made of problematic minerals & they also degrade over time. Transmitting the signal through air is also much less efficient than transfering it through a wire.
Why does fairphone support that, over just normal wired headphones?
And no, I don't want to be carrying an usb to jack adapter all the time with me, as it's inconvenient... +1 thing I can potentially forget to take with me, or lose somewhere.
Also, all bluetooth versions which are used in practice are very significantly worsening audio quality. Only some very special and widely UNsuported BT variants are good enough not to be audibly lossy (+also the one with "lossless" in it's name used the term "lossless" like if it was some meaningless marketing buzzword they can just throw around, as it is just another lossy compression and totally not lossless.)