AR gives you a way to receive situational intelligence. Paired with AI and cloud connectivity, that's incredibly powerful.
It's really just the next step in human-computer interfaces, making computing more seamless. Apps can be more aware of your surroundings and superimpose data in-situ, rather than forcing you to refer back-and-forth to a tiny screen. Take Google Maps, for instance. Imagine your route highlighted right in front of you. As you walk past restaurants and other businesses, being able to see information like user reviews, typical meal prices, peak activity, and years under current ownership, without having to fuss with looking it up on your phone.
Perhaps a service or sales person can make a customer visit and see people's names and details recorded from previous visits hovering above them, so that you know who you're dealing with.
In a repair context, you can not only see relevant documentation and videos, but they can be automatically keyed off the images collected from your camera. If you require online assistance, the remote agent can see what you see and what you're doing, without you having to juggle a phone.
In the case of firefighters, a floor plan can be matched up to indicate where the walls and doors should be, in case the smoke is too dense. They can also superimpose imagery from IR cameras and microwave sensors to help see where there hotspots and obstructions.
In the other thread,
@Dantte had
an interesting example of using it for powersports.
There are so many examples, it's like trying to sell someone on the idea of a smartphone whose never seen one. You know it's better than a regular cell phone with SMS, but it's hard to really convey what a monumental shift it is other than to enumerate a litany of different apps and use cases.