I think training of this variety is important for any martial arts school that even hints at self defense. Knives are dangerous, period. If you get into a confrontation with someone who has a knife, you're gonna get cut, you're gonna get stabbed, and you're gonna get hurt. What's scary is, a lot of the time, you don't even know you're getting hurt when it's happening because everything can be very fast and disorienting and the pain signals you'd expect for getting cut and stabbed aren't there. Combined that with the fact that in situations of high stress, you almost never react the way you think you will, suddenly it becomes scary, scary shit.

One of the things a lot of people talk about is situational awareness, knowing what trouble there could be and where it comes from. Personally, I'd take things a step further and go for situational avoidance. Avoid rough bars, unlit alleys, etc. etc. Is it always possible? Of course not. Can trouble find you in places where you wouldn't expect it to? Absolutely. Crime is also a numbers game though. Anything you can do to decrease your odds of finding yourself in trouble should be done. Not only for your personal safety and the safety of those around you, but because finding yourself in altercations can find you on the wrong side of the law, even in self defense situations.

Out of curiosity, how much grappling experience have you had? I know Wing Chun doesn't focus much on grappling, Chi Sau notwithstanding, but it's a good skill to have in your repertoire. There are people out there who are more comfortable grappling than they are striking, even untrained people who get into an altercation. Knowing how to prevent take downs and getting out of holds goes a long way, it keeps you from being on the ground for a prolonged time so your attackers buddies can't get to you. Plus, things like BJJ, Wrestling, and Judo are good fun and a great workout.