It's implicit that "more useful" means for users - but removing the headphone jack is more useful for the manufacturer (which makes it terrible by my standards too, but not inexplicable).

Removing it opens other doors, like waterproofing and more room for hardware. Thinner phone maybe too. Bruh your users into the 21st century. It’s about ditching the guys who want you to freeze in place, which I know there are many of here (not to say you in particular are one of those)

Design, as the op even says, is not just (although it definitely also is) about utilitarianism! The world of successful products should at least suggest that to you, if you won’t take it as proof.