I suppose it depends upon the lifestyle, but I disagree whole-heartedly.
All of those features are useful, but I do not need them, and I do not wish to be tethered to them either. Plus, I've seen too many depressed mums staring forlornly into their coffee mugs at a cafe while their children cluster around them, curled into the foetal position and gazing unerringly into their respective smart phones to regard the technology with anything save reservation.
You can also live without electricity, the printing press, gasoline powered cars, and a whole bunch of other stuff. They are not even strictly necessary to survive in modern society.
As for the whole 'staring into their phones in the fetal position' bullshit. They said the same thing about NOVELS back in the victorian period. Almost word for word.
Smart Technology, in the form of smart phones, effectively externalizes our memory, and as long as we're plugged into a network, gives us conditional omniscience. Knowledge is a massive reason humanity, as a species, rules this mud ball now. Conditional Omniscience is a huge evolutionary advantage over just about every other bit of technology that could possibly be provided to us.
Is it STRICTLY necessary to functioning in society? No. Will you be at a horrendous disadvantage if you don't use it? Absolutely.
9 times out of 10, also, those kids 'staring into their smart phones' are still interacting with people. Maybe not physically, but they are interacting with them. That's not likely to change. Multiplayer communication will always be more fun that solo.
edit:And any parent who can't keep a reign on their kid on those situations, who are unhappy with their kid in that situation, is obviously not putting the effort into actually PARENTING.
I have to look after my nephews and nieces sometimes (more cousins actually but they're so much younger than me I get called uncle), and because I develop games for a living, their parents come to me for advice on how those things interact with their children.
I tell them straight up. "Take the time to research the stuff. Would you bring your children to a movie you hadn't at least watched the trailer for? Of course not. Don't buy them games you haven't at least done the same for! You don't have to trust the ESRB rating system, but it's a good place to start."
I also tell them to take the time and effort to BE with their kids when their kids play games. Don't let them have a personal computer in their room until the child STOPS (full stop) playing with other forms of toys. Don't let them -ever- have a game console in their own room rather than a shared living space. Until they reach the point where they stop playing with physical toys (at least to the degree that you feel it's time for them to move onto other activities), don't let them play their console without you BEING IN THE ROOM. It doesn't have to be you playing the game with them even, just be sitting there reading a book, watching what they consume as a form of media, making the judgement calls on what's appropriate and what's not.
I -despise- people blaming technology rather than how people use it. These are -tools-, they are not mind control devices, they do not make us weaker or stupider or anything like that, if anything, these things are making us SMARTER as time goes on. But you have to THINK about how they're being used.
edit2: In conclusion. A smart phone is like carrying the entire library of congress in your back pocket. That's not necessary, but it's a damn huge advantage.