Yes, but its more than pining for the good ol' days. It about logic!

Just for the sake of argument, IF I decided to assasinate a senator in his office and IF I had managed to get an appointment, then I would go into the building with a plastic knife hidden in my underwear. I would go to the restroom and pull said knife and palm it. If I wanted to kill several senators, I would take out a cop or guard first and then use his sidearm. If someone were to outlaw plastic knives, I would buy any object made out of hard plastic I could find and a Dremel tool, them I would make my own. None of this requires any special training, and no security system could detect and stop it before hand. Intelligence/monitoring couldn't even stop it as long as I kept my mouth shut and didn't tell anyone what I was planning to do.

That's just one way, others have pointed out that any glass item of sufficient size (e.g. a bottle, a picture in a glass frame) could be used in the same way.

Taking knitting needles from old ladies ACCOMPLISHES NOTHING!