Speaking for myself, I own a Buck Hunter knife that I used to carry as a pocket knife. When I learned that it's not street-legal (it's blade locks, and is 1/2" too long) I stopped carrying it. So that's one anecdatum. I'm not particularly unusual; I imagine many people that once carried a locking pocket knife no longer do.
There was a spate of stabbing reports, about a decade ago. That seems to have died down. My guess (and it's only a guess) is that only drug dealers and people bent on mayhem carry guns or knives that aren't street-legal these days; what's the point in getting busted for carrying a penknife?
Incidentally, I don't get the point of the ban on locking knives. If you stab someone with a knife that doesn't lock, then I suppose there's a risk to your own fingers; but the dude you stabbed won't care if it was a locking knife or not. I do get the blade-length restriction though. You don't need a 3" blade to sharpen pencils.
My straight razors are street-legal, though, and I think they're quite a lot more dangerous than a 3" knife that locks. The sharpened edge of a razor is only about 2" long, so I assume it's street-legal; but you could really make a mess of someone's face with a razor (the preferred weapon of Pinky, the gangster from Brighton Rock).