Doug,

From just looking at the slide show of pics put together by the DA, I would think safety of the user comes into play. I noticed the typical box-cutter, that is in every tool kit in America, pictured and would think if you take the one handed blade deployment away, that most of the time they would be left in the open position between cuts and there you go with an important safety consideration. And even tossed back into the tool box in the open position.

While the DA in NYC might not be able to relate to me being able to cut a rope on a horse in a panic situation with one hand, he should be able to picture someone cutting up some carpet or whatever that requires two hands and putting the open knife down between cuts.