It's far better to have a mobile phone that might not work in an emergency than not having one at all. Is it not? I mean pay phones don't just vanish if you buy a mobile phone.
Furthermore, their merits far extend their practicality in emergencies.
Outside of connectivity with other people, they are fantastic platforms for news, both local and global, entertainment, work use, arranging/managing your life, fitness tools, addresses etc.
But by far, the most important asset a mobile phone has to offer to anyone is it's ability to connect to the world of Internet with respect to the vast knowledge you can access immediately!
I'm forever using my phone to find this out and understand that. Knowledge is the greatest asset humanity has, it's fundamental to our success, more notably, inheritance of knowledge. Having an immediate portal anywhere to access this is hugely advantageous for everyone.
If you don't want a phone, don't have one. But it doesn't mean they hold no merit.