Some days I can go an entire day without using my knife. But when I need a knife, it's nice to have one in reach. When I was working in the machine shop, I actually could get by without one, as there were Stanley utility knives on every work bench. But being retired, I actually need a knife more now. There's fishing with the grandkids, canoeing with the better half, woods rambling with the better half nature watching, and cooking out more. Being retired means more screw off time doing all the things I day dreamed about doing while I was stuck in that shop. And a knife is a nice thing to have off in the woods.
But in suburbia, I do have to admit that while I like to have a knife, I don't need much of one. Even a very small knife on a keychain like a Victorinox classic, will open boxes, plastic blister packages, mail, cut twine, and even provide small scissors. Modern urban or suburban life styles do not need much knife, but I think everyone should carry at least a minimum knife on a keychain. If, God forbid, you run into an emergency, and something about that emergency needs a knife, then you're going to need that knife very desperately. Twice in my life, I've needed a knife to help someone else, and it was possibly life saving in one of those instances. My Buck stockman did it. Even a SAK classic would have been enough though. Sneaker laces and seat belts are too tough to chew through.
I'm of the opinion that while most of us knife knuts carry a ridiculously over sized knife, every kid that reaches 16 years of age and gets a drivers license, should then get a SAK classic, Spyderco ladybug, A.G. Russell ulitimate pen knife, or something, (!) to go on thier keychain so they will always have a sharp blade on hand. If we trust them with 3000 pounds of car, then a small sharp knife is nothing. How many people have died stuck in a wreck or like that old lady choked to death in Boston, because nobody had a knife to cut the scarf caught in the escalator?
If you need it, nothing else will do.
Carl.