One, the headphones would be compatible with anything that has bluetooth, not just iphones and ipads.

And there are way less devices with bluetooth than with traditional headphones jacks. Also, in my experience pairing and un-pairing bluetooth accessories is really hit or miss and ultimately if it's too much of a pain I won't ever bother switching what they are paired to. It's certainly never going to be as easy as the old headphone jack where you just plug it in to anything and it works.

And two, with one fell swoop Apple would introduce millions of bluetooth headphones into the market in a matter of weeks, pushing adoption at a rate we haven't seen before.

True, but if you lose / break them, it's still an expensive thing to re-buy and it's going to be awhile before they are as cheap and ubiquitous as standard headphones. If I'm at the airport or on a random street and I forgot my regular earbuds I know I can just pop into a convenience store and easily find a $10 pair of cheap earbuds that will do the job. Finding a new pair of bluetooth/lightning earbuds is likely going to be more difficult and expensive.

Also, bluetooth headphones will need to be charged no? I don't really need yet another device I have to plug in at night that might run out of battery when I need it.