Imo a knife could be compared to a watch, you don't need one but It's nice to have day to day, and was an essential object a couple decades ago.
A lot of craftsmanship goes into both.
As for carrying one everyday, remember that 50 years ago almost every man had a pocket knife on him, they're not for defense or to intimidate people, they are tools. Man's oldest tool.
I use mine to sharpen pencils, cut food on the go, open caulking cartridges at work etc... I can honestly say that I use mine everyday, they're just practical.
I might sound cliché when I say it's better to have one and not need it than needing one and not having it (Cutting a jammed seat belt comes to mind).
I can see why carrying a gun shocks some of you but a knife? Come on, most of the guys who posted in this thread also have guns, they must have other reasons than defense or intimidation to carry one since the gun can serve that purpose.
Sorry for the long rant but It just seems that some of you are arguing for the sake of it.
edit : didn't see another thread was opened while I was typing this.