Because the switchblade distinction was arbitrary and ridiculous. There are a ton of folding knives made today that one can open with just a flick of a thumb or finger. Those knives open every bit as quickly as any automatic knife, and yet were not illegal.

The old law also made no distinction for knives that were clearly used for legitimate purposes. My mother was a career HS teacher who travelled to Italy a few times. On one of her trips she brought home a switchblade; the blade was an inch and a half long. Mom kept it in her purse and used it to cut the fruit she brought for her lunch. Should she have been charged? That's ridiculous

My mother was not going to throw down a la the Sharks and the Jets with other teachers in the parking lot.