I heard a variant of this recently. I told a colleague I don't use my phone for long periods, days at a time, that I miss nothing, am a happier person, do stuff with my time that makes me happier, etc, and she broke out in a mild panic, along the lines of:

"What about emergencies?? What about when you need to phone someone about X, or phone someone else because Y happened?"

It's a good argument - the typical phone in 1998 was a useful and practical device. Seriously, being able to ring people has many excellent and real use cases. Phones aren't just calling devices anymore, though.