Agreed the comparisons with optical and floppy drives don't hold water for me because those are relatively huge components and were replaced with something at least arguably better
Exactly, this is completely different.
An iMac is stationary, so getting rid of the floppy might have been inconvenient, but you just buy an external drive, plug it in once and leave it. Plus, the cd-drive which replaced it was far superior, and more universal, cd's were used in more places then just your pc.
Removing the cd-drive from laptops too made a lot more sense. It allowed for substantially bigger batteries and much thinner laptops. Internet speeds had gotten to the point where most of our media came from there. And there were already large format USB memory sticks available too.
When they got rid of the iPod connector in favor of lightning, that too was for a much better port and it was a 10 year old proprietary port used on 3 devices (iPhone, iPad, and iPods) being replaced by another proprietary port used on those same 3 devices, not a 50 year old universal port used by hundreds of thousands of devices being replaced by a proprietary port used by only 3.
This would be like Apple getting rid of the USB connector in the macs and replacing it with FireWire 2.0 instead of something universal (like USB-C which is has done in the MacBook).
While I love the lightning connector and think it's the best digital connector available, unless Apple plans on opening that up so everyone can use it, I think it would be bad the get rid of the headphone jack. I don't want to have a pair of headphones that only work with my iPhone, and then have to get another pair that will only work with my android phones, and then have another that will only work with my MacBook.