Charge my phone, charge my watch, and now my headphones, too? That's FOUR things to keep track of how much charge they have! How could I ever be expected to remember to do that, let alone want to?
Also, what about forgetting they're in and going for a swim, or a shower? What about bumping into someone or tripping down the stairs and losing them forever?
What if I want headphones that have noise cancellation, or want earbud types? How much do I want to spend on specialized headphones that also have bluetooth machinery inside? With wired sets you could just plug them in and they were guaranteed to work. Now, what if the bluetooth implementations between the phone and the special headphones I got are incompatible?
They suck!