Your arguments about this issue are thoughtful. Many of the other naysayers seem reactionary and hysterical. Your point about timing is interesting, and is obviously relative to each individual, depending on the status of other technology that you own. If your car already has Bluetooth, if you have an Apple TV with airplay, if you have few Jawbone Jamboxes, and you already use wireless headphones like the Jaybird X2, then this transition will go almost unnoticed. That's my situation. If you still use a wired connection with all your existing gear, you'll need an adapter until that gear is upgraded.
But considering that the entire industry is an order or magnitude bigger than it used to be, and how exponentially faster new technology is rapidly prototyped and implemented, I actually think the "relative effect" of the timing of elimination of the 3.5mm jack and the shift to wireless audio will be about the same as the optical drive change. Also, I remember that back "then" wi-fi wasn't nearly as good/reliable a replacement, relatively, as Bluetooth audio is today. Transferring important files (especially big ones) wirelessly was a pain in the arse! So in that respect I think we're actually ahead of the curve.
I'm not an Apple fanboi that believes everything that comes out of Cupertino is beyond reproach. But in this case, I think they are getting it as right as they can. Plus, I believe part of the reason for this timing is that Apple is laying the groundwork for radical formfactor changes to upcoming iPhones that will be predicated on not having that extra port (e.g. eliminating the "forehead" and the "chin" in order to have the entire front face of the phone be screen).
It takes balls to push things forward, and Apple takes a lot of flack for it. Thank god someone is willing to do it. It's always a bit of a hassle when change happens, but we all adapt. I respect that sometimes, depending on your other ancillary gear, it can feel like more of a hassle than for others. Sounds like that may be the case for you, which is a slight bummer. I'm a filmmaker, with dozens of 3.5 mm audio cables/adapters/gear I've invested in over the years, so I get it. Hopefully, in a few years, we are all looking back at this kerfuffle with a smile.