If you're walking down Main Street, you won't get suddenly swept off by a cyclone like Dorothy in the Wizard of Oz, and dropped onto Gilligan's Island where you'd be in big trouble if you didn't always carry a 10 inch Bowie knife good for hacking through jungle with. I just wouldn't worry about it. The most common use for a big pocket knife in ordinary experience is for cutting food, i.e. if you want to slice through a loaf of bread or a big block of cheese, without having to go at it from all 4 sides. But you can always improvise. Really, for everyday situations, a regular size SAK is generally more handy than some huge blade, and it can be pressed into other duties as needed.

Of course if you're going out in the boonies, or equipping a ditch bag for a bush pilot plane, you may want to pack a bigger knife; but you'll also be away from those urban jurisdictions where big knives are restricted.