Oh, at my last job I used my Leatherman a ton. Wire cutters, screw driver, pliers, etc. I used the blade for opening boxes and stuff too. I don't know that I'd say everyone needs one, but they are pretty handy. I don't usually carry it anymore at my new job since it's pretty different, but I still occasionally find myself reaching for it.
To the OP question, I would say everyone should have a "go bag" with essential stuff you need in an emergency that's already packed and ready to go. A multitool is a great addition to a Go Bag since it can take the place of a lot of tools in a compact way.
Loop makes earplugs designed to do this. They have different models, like their Experience one is designed for going to concerts that are too loud, but you still want to be able to hear the music properly, just quieter. Or Engage let's you hear voices, but it helps block out background noises. They're pretty discreet and most people won't notice you're wearing them in my experience.