I sorta wish it WOULD get trendy. There was a time (at least in the US) when a man who didn't have a pocket knife was a rarity. I was a kid in the 60's, and back then most guys had a pocket knife by the age of 7 or so. We had them in our pants pockets pretty much all the time. The schools didn't think a thing about it, and I NEVER heard of someone getting into a knife fight or 'Pulling' a knife on someone.
You know what there was the same thing in my grand fathers day here in canada he was ww2 vet and though I never met him (died a month before I was born) my dad has told me the little we know about him ( after the war he didn't talk about himself) and one of the things he said was that my my grandfather always had a knife in his pocket and no one thought anything about it.
Nowadays though schools are way too strict for example if you wear work boots the principal has been known to "talk" to you about it and i once got in trouble for having one of those utili-keys ( the ones with a 1inch blade on it) on my keychain