First of all, you can be married to your cell phone or not, (it's your choice). IMHO -Being married to a cell phone means you must watch everything that pops up on your cell phone.Some people might walk into an open manhole by constantly watching their screen. I am not one of those people.
1. I find it useful as i have been stranded twice on the road and it was a convenient way to get help. I find it comforting to be go out and have a level of protection in being able to call someone for help.I find it discomforting in that if I leave my phone at home, I have no way to get help.
2. I got rid of my land line as it saved me from having to answer the phone for telemarketing calls. My home is now quiet, I just recently got 20 or more calls that my cell phone marked as spam.I blocked all those calls.
3. A cell phone would free you from having to stay home if your expecting a doctors call or anyone else who needs to make an appointment with you.
4. I find the cost to be reasonable to own a cell phone. My plan is $59 per month. I believe the cost to pay for the phone itself was included in the plan I selected.I believe it is worth it to access info like hours of operation for a business, looking for phone numbers, etc.
I understand your reluctance but the benefits outweigh the cost and need. IMHO
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"It doesn't cost "nuttin", to be nice". 
MOM
I just want to do the right thing! Uncle Joe, (my hero).