Gene Simmons (No Relation);
First, you did not offend me. You offered a "teachable" moment.
Second, I thank you for reading and contributing in your creative manner. I get the joke -- at least, I think I do... In any event, I enjoy your slightly weird comments, and even look forward to them.
You are touching upon the subject of an ongoing discussion I have with my good friend, SkyNinja. On the subject of what will keep me alive, I defer to SkyNinja's practical expertise. His advice on knife defense -- based on his training and experience -- is not to use a fancy knife disarm. Instead, you should use a "ballistic" defense. Basically, it's what you described: hit the guy as often as possible to overwhelm him -- avoid the knife -- escape from the area. These three actions should be accomplished in whatever order best allows you to survive with the least injury. Oh, and it sounds like you should do the actual hitting with the best weapon available to you.
I trust you will find this advice to be practical. I'm feeling practical and tactical today; I'm wearing my jeans today, not my jammies.
On the (theoretical) other hand... "Fancy" knife disarms exist in many different martial arts. And many of them come from eras and cultures with a great deal of experience with blades. It's hard for me to dismiss them outright.
This may be a situation in which the circumstances that gave rise to a martial art play a role in understanding the techniques. For example, a knife defense from Japan may have been developed assuming an overt attack on a battlefield and an armored defender. That's a very different -- probably more survivable -- situation than a prison shanking.
Also, there may be a faulty assumption at work with knife defenses: just because the technique exists doesn't mean it will work 100% of the time. We don't have that expectation of any other martial art technique. Even the most basic punch fails to land a percentage of the time. We don't say the Guard doesn't work just because it can be passed. We may have to acknowledge that a knife disarm may only work... what 1% or 5% of the time. It's still better than having no technique at all.
There may also be a viscious circle. If the technique is low percentage, you might not train it often. Then, if you don't train it often, its effectiveness is probably reduced.
But your other question; what should you train for? That's a good question. It's going to depend on your circumstances. If you're in a risky environment and constant danger then my advice would be to practice basic techniques with a high percentage of success and seek out teachers with practical experience. If you're interested in martial arts for their own sake and aren't worried about your day-to-day survival, then I think you'll get more mileage out of a "traditional" martial art -- jammies and all. If you want to compete, then you need to find a fight gym and prepare to spend a lot of time boxing and wrestling.
I hope that doesn't sound too mystical, grasshopper. Martial arts isn't a one-size fits all activity -- no matter how many folks insist it is. There is no single way of doing things best.