Apple has been pushing the envelope for a while. Remembering the iMac and then, the PowerMac, Apple removing the floppy drive was viewed as horrific.
How would we transfer information? CD recordables weren't that common. There was a new bus--USB, instead of Apple Desktop Bus that connected the keyboard and mouse. We could connect other peripherals but there were only 40-some available at the iMac launch.
When I got my PowerMac G3, with the ugly blue front panels, I needed some way to load things from floppies. I bought some Imation (3M) drive that could utilize floppies and a special, high capacity drive.
Here were are about 17 years later and Apple has removed the headphone jack on the latest iPhone models. They've included an adapter so that you can use your current headphones with an analog cable.
This change was important in order to make the iPhone dust- and water-resistant. With higher resolution audio, getting rid of the analog headphone jack made sense. For years, people have been using a personal headphone pre-amplifier to listen to Classical music. This change should make everyone happier in the long term. Hopefully, high resolution audio over Bluetooth will be satisfying also. Certainly enough people use Bluetooth speakers and car audio systems that communicate over Bluetooth.
I can imagine that early reactions will mostly be negative, even from people who don't use their headphones at all (such as those who hold their phones slightly away from them, on the horizontal). People don't like to change.
Update 2016.12.19: I've had my iPhone 7 for around two months now. There have been a couple of times when I wanted to lie down and listen to music with headphones while I was charging the phone and I couldn't. Oops. I ended up buying an Altec-Lansing Bluetooth-enabled speaker.
It has not been a huge problem. Even the included ear buds are good. I've tried the adapter with my Sennheiser CX300 Mk II ear buds and the sound is good. There is no scratchy, static-y sound using the adapter, something I experienced with some ear buds and the headphone jack.
Even Walmart has Bluetooth-enabled headphones and ear buds. Prices go anywhere from US$20 to around US$300, from what I've seen. I suspect you still have to go somewhere around US$100 to get high quality sound. Finding good, strong music transmission will likely be the problem. Somewhere, I have a pair of Motorola headphones--S9, perhaps--from nine or ten years ago. They were never great but they would do in a pinch. I used them while mowing the lawn mostly.