I wouldn't say they aren't useful. I think it depends on your lifestyle. It was definitely useful when I worked on base. And sure, I could carry around all that stuff, but why would I when I could just carry a phone that has all that and more. And I wouldn't want to have to go home just to contact someone. Or have someone have to call multiple numbers to reach me. It can be pointless for some people to have cell phones. But for others, it's very useful as a tool and more...
Maybe if you're not near a phone then ok. I rarely need a camera or GPS and will take them when necessary. My point being how can anyone tolerate the freaking costs. Or worse try to rationalize them. No wonder younger generations have little savings.
newsflash most of the time when people need to make a call they aren't at home ---