As a woman most often unaccompanied and on her own when out-and-about, and of course concerned about being able to get in touch with others if something happens while I'm driving my car, I always have my iPhone with me when leaving my neighborhood.
Sure, walking around my neighborhood to collect my mail or take out the trash to deposit it in our community dumpster or recycling area, I don't take my iPhone with me. Also, when out in the neighborhood shooting photos, I don't expect to need the iPhone, either, nor do I want any interruptions while I'm in the midst of composing, focusing and taking photos. The iPhone stays at home and that's fine, as I'll be back in the house fairly shortly anyway in case some important call(s) did come in during my brief absence.
When somewhere else away from home, whether I've driven myself or have gone somewhere with someone else, I like having the iPhone with me "just-in-case." Just feels better, safer, somehow....
At home, the iPhone sits on a stand in the living room area and so is reasonably close by when I'm on the computer and a call comes in. I can glance over at it. If I'm in another room and don't hear the phone, well, if a voicemail message isn't left I'm not likely to remember to check the phone and therefore know that someone even tried to call me at all. Hopefully if it is an urgent situation the person will think to text/message me or send me an e-mail, as in both of those situations I'm more likely to become aware of having received a message sooner rather than later.
I no longer have a landline phone; that went away several years ago so that the iPhone is basically it now...... I really don't receive or make many phone calls these days anyway so it's not a huge issue one way or the other.
I hear you, and understand, to a very large extent, where you are coming from.
For what it is worth, I still have a landline (and will never dispense with it); it is too convenient, and, frankly, the acoustic quality is a lot better than is the case with mobiles/cell phones, and I like the idea of a device that simply makes phone calls.
Perhaps, surprisingly, I used to actually like my phone in the old clam phone days; above all, I loved their portability - shoved into a jeans or jacket or coat or chino/khaki pocket, and you were good to go; these days, hardly anyone phones me on my mobile/cell phone (perhaps, they have learned that I am difficult to find), although I will always answer texts (but, rarely, immediately).
Now, I loathe smart phones (yes, I don't doubt their convenience, or the range of what they offer), their grotesque size, their ubiquity, their senseless interruption of normal, civil, human interaction.
Yes, when working abroad, of course I will use the devices that I have been given (though, in my most recent election observation missions, I had to ask my staff to show me some stuff - such as how some things worked - on these horrid devices; needless to say, my staff were completely at home with these things and had no trouble in patiently explaining things to me, and doing the needful on the phone - some Galaxy thing - that I had been supplied with).
If a good quality - nice, elegant - clam phone appears, I may well investigate, and consider making a purchase.