You're missing the point, to answer your first question yes I have. But more importantly it's not about using any old knife as an improvised weapon. It's about being able to tell the difference in design features of a dedicated bladed weapon, and a utility knife.
How many of you EDC a fairbairn sykes, a Rondel Dagger, a huge Bowie knife, or a tanto. Probably not many, and there's a reason you don't because they aren't made to be utility knives, and even if you don't consciously acknowledge the difference between a combat knife and a utility knife, you subconsciously know they are not designed for everyday cutting tasks.
Why aren't warehouse staff issues with Trench knives, because the last warehouse I worked in we got issued with stanley utility blades, because what a shocker, they are made for those tasks we did.