I think it is safe to say that the compelling reasons to continue the practice of kata and bunkai supersede gaining security based on kata's efficacy. As an art form kata rescues the beauty of combat from the chaos of brutality and war.
The techs that kata contain have plenty of violence in them, b. A very straightforward oyo for the first few moves of Taikyoku Shodan uses hikite and an arm pin to force a grabbing attacker's head down, smash a horizontal elbow into the side of his face, continue with the elbow past that impact and then spear with the elbow point downward back into his face, and followup with the fist on the spearing arm coming down hard—the so-called 'down block'—in a hammer fist to the carotid sinus. That hand becomes the gripping hand through muchimi, and a forward transfer of weight and an accompanying punch to the throat with the other fist—or a palm-heel strike into the face—will pretty much bring the attacker to the ground. And after that initial arm pin, all the moves are forced. The only beauty there is the beauty of efficiency. I train this and other bunkai from the hyungs and kata I study, with partners who aren't making things easy at all. The contact is constrained, but if it weren't, the result would be every bit as unpleasant as it sounds. And I teach these kinds of techs to my classes. That's the information that is in the kata. There's no prettifying them, b.—they are instructions on how to destroy an attacker's will to fight by hurting him more than he can take.
Though Matt would call it a dead practice because of the assumption that there is no resiting opponate. I refer to it as "Alive" because you are facing off against the most deceptive and subtle of opponents, your self.
I have to say, I don't see anything at all in the kata about
oneself as the opponent. The kata are telling me where to attack weak points on my
attacker's body, in a way which keeps him out of the game—always a tempo down, as the chess players say. My own belief, which I've seen some evidence for in Motobu's and other karateka's writings, is that the intention never was endless solo rehearsal of kata—a
partner for training the applications was always assumed. People think performing kata is practicing kata; I disagree. Really practicing kata is doing the bunkai, then working the oyo with noncompliant training partners who resist—hard. It's that way in other MAs; for some reason, people have confused the
performance of kata with the martial
practice of kata, but they're quite different. Once you've learned the kata and have begun to unravel their destructive content, you need to practice the techs you've discovered with a noncompliant partner so that you can implement that destructiveness. Iain Abernethy, Peyton Quinn and Geoff Thompson have written about this indispensible aspect of kata training in detail—IA has a great article
here that goes into some detail—and no curriculum which omits it can claim to be getting anything remotely like full SD value from the kata students learn in it.
Kata are manuals for damaging people who are attacking you physically. If you want to make more of them than that, fine—but that's what they were originally created to be. As Motobu himself has indicated in his writings, in the early days, the kata weren't
part of a martial art, they
were the art. Rohai, Empi and the rest were considered
styles unto themselves. They were what Matsumura, Itosu, Kyan and Motobu
did to the people they fought with. If it was good enough for them, it's good enough for me.