Let's not kid ourselves that there was ever a golden age of chatting to strangers on, or waiting for, public transport. Certainly not in my experience in the UK - and as an oldie I spent years commuting when the best mobile technology could offer was a massive corded telephone handset installed in a posh car.
People who weren't asleep would have their noses in newspapers and books, or would stare vacantly into space - or out of the window. The advent of the Sony Walkman added a new class of people with their eyes closed listening to tinny drum snares. There are too many humans living in cities to be able to cope with that many people at an individual level. The brain objectifies humans into a mobile obstacle course to navigate before landing at work.
I don't think that's a problem with a handheld device.
People will continue to meet up face to face, have and go to parties, talk to friends in cafes and restaurants or over a board game. The idea that we are all locked in individual rooms with laptops is an appealing "future shock" image, but false.
Spending hours glued to a screen is the reality for those of us privileged enough to live in the west. It gives you doses of what you enjoy - winning, being right, attention and routine/ritual. Social media, games or whatever floats your boat - in your hand, in your pocket whenever you want - with little audio and tactile cues to keep the saliva dripping. It's insidious and fully supported and embraced by market forces. Some people will resist that allure - and there's nobility in that - but others won't, and that's just fine.
I don't buy the idea that just by looking up from your phone, you will find the partner of your dreams. That suggests that you're not using your phone for Internet dating or building rapport with other people and that talking to strangers in the street is a more worthy/efficient/effective use of your time. Also the compressed life story (dating, marriage, house-buying, children, grand-children) is placed against a few moments on a phone. It's not really a good comparison. Heavy-handed at best. What are we saying here - if you use your phone for games, you will never have a happy family life? I suspect there are other factors.
Perhaps it's not the phone itself and where you're looking, than what you are doing with your phone. If you are arranging fund-raising for a local charity that helps disadvantaged kids into education and using your phone to spread the word - then, in my eyes, that's a win. You keep looking at your little shiny oblong window of delight and ignore any ranting I may do about 'kids these days'.
I suspect that most people aren't using their phones in this way. But then not everyone has figured out what creates happiness in the long-term. The world has always been about trying to find brass in the muck. The phone in your pocket just brings muck and brass alike closer to us more of the day.