In my lifetime, I've collected way more knives than I ever needed, and a lots those knives were knives that I had no use for. Except for 10 years in the army, most my life was in and around Washington D.C. working as a machinist. I had need of a knife, but any old small pocket knife would do. Cutting open boxes of parts to modify, cutting the grimy steel dust coated tape off the bundles of round stock by the lathes, peeling off the burrs on some delrin parts that got modified on the mill, trimming two sided tape for sticking parallels in vise jaws on the Bridgeport mill. Lots of uses for a knife, and most my co-workers used small pen knife or a Stanley 99 or a clone.
Most my backpacking, fishing, and camping cold be handled by any SAK or my old Buck 301 stockman. I had very little need of a fixed blade and in time I sold off my small Randall collection and most my fixed blades. I got rid of most my knife accumulation and now have a handful of a few traditional pocket knives and SAK's. The one fixed blade I kept, my old Buck 102 Woodsman, takes care of cleaning the fish I catch and campfire food duty.
I think a pocket knife is a necessary tool for anyone, urban or rural, but how much knife is the question. For most my life as a knife nut, I realize most knives I've carried has been serious overkill. I came to the conclusion years ago that more than a pocket knife with a few inches of blade is overkill. Opening packages, breaking down a box, cutting some twine, doesn't need that much blade. Heck, they even castrate bulls and field dress deer size creatures with a trapper size pocket knife.
BUT...having a knife on you is like having a spare tire in you car trunk; you may not need it today, or even tomorrow, but if you really need it, nothing else will do. Like in January of 1991, when a car driven by an idiot rolled three times and came to rest on the partly crushed in roof, and started to burn. Crawling into the car, it was no trouble getting the seat belt to release the baby seat with the screaming infant. But the obese lady driver was hanging upside down and her seat belt would not release by pushing the tab. I had to use my pocket knife to cut the seat belt as the car was filling with black oily smoke. Nothing else would've done, and there wasn't time to find something.
No, we really don't have much need of a knife in our modern suburban society. But when we do, it could be really important o have a little bit of sharp blade on hand. Like my old man told me when I was a kid, it doesn't have to be big, just sharp. But it does have to be there on you. It doesn't take any more knife to cut a seat belt than open a package. But you need to have it.