Removing legacy components is not necessarily a bad move, per se, as long as there is a better replacement.
When the original iMac was released without a writable drive, it effectively turned the machine into a "read-only" computer. It wouldn't be until three years later that the iMac came equipped with a CD-RW. In the meantime, anyone who wanted to be able to swap data back and forth with their iMac had to buy and external disk drive. The "i" in iMac stands for Internet, but the internet in 1998 was still mostly dial-up at home, and not a suitable means of large data transfer.
At least, by the time the optical drive was removed from the MacBook Pro in 2012, most software was being distributed via the internet, whether it be a direct download or the Mac App Store. Plus, Apple had had a couple of years to get things prepared with the introduction of the MacBook Air in 2008.
My biggest gripe with the removal of the standard headphone jack in the iPhone 7 was that it made it difficult to be able to charge up the phone and listen to music at the same time. With the introduction of AirPods, and now the inductive charging in the iPhone 8 and X, it helps to assuage some of these concerns so the sole port isn't being overloaded.
You highlight a great point: retire one function when you have another function to replace it. To improve it. Not retire now and release the successor years later.
I own a 7+. I bought a great pair of BT headphones for it. End result: I now listen to music from my phone far less than I used to. A change that was designed to improve function and resulted in reduced use of that device.