If only there was a book that stated what exactly what use the kata (form in my art) really served. I think everyone is both right and wrong about this.
My sensi, TKD for those wondering, does not believe that what the MCdojo calls a Block, is a block. We study every move as a strike.
Our reasoning behind this, even a soccer mom at a game can block an attack from a supurbly kicked soccer ball. Blocking is a natural response, no need to practice block.
As for defensive or offensive, lets think about this.
It is correct to say that kata is a grouping of attacks on one person, or a sequence of attacks on multiple people. We study our kata(forms) and can apply each series to fighting on person or two or three.
Another "rule" we have is the 4 concepts of an attack.
1. Nutralize the attack (block, which we say strike to pressure points)
2. Strike (sometimes 1 and 2 are together)
3. Grapple (after the strike, you should be able to grab a finger or wrist or foot and perform a joint manipulation)
4. Control (this part is from the LAW Enforcment side, for cuffing, or controling where the opponent will go)
A good defensive action is nutralizing the attack, striking the attacker, grappling (not wrestling), and controlling the attacker. This should happen in one second.
1) Kata was never meant to be a choreographed fight against multiple opponents. I've said this 264 times (a million seemed to be exagerating) . The idea is to pull individual pieces away from the kata & then train, train, train. If you do that, people may think you're doing Krav Maga.
2) A good Offence is the best Defense. (nuff said)
3) We need to get over the notion that a pre-emptive strike is an attack. Following our consciences to be the "honorable" ones, we can end up on the knuckle side of a right hook. I like to think in terms of 3 basic defensive maneuvers:
a) Go-no-sen: Block & attack
b) Sen-no-sen: Block w/ attack
c) Sen sen-no-sen: stolen timing (pre-emptive strike)
Most of us would do well to utilize Go-no-sen in an actual SD scenario. Some may manage the next higher level of SD, Sen-no-sen, to change the course of the aggression. A very few who aren't hobbled by nerves, inexperience or surprize could possible deal w/ an attacker via Sen sen-no-sen.
This highest level has a nearly "psychic" quality that we all strive to acquire through years of training. This is what Funakoshi was referring to.
Now if you approached that guy in line who was "looking @ you funny" & kicked him in the marbles, don't look to me to back-up your Sen sen-no-sen arguement. Not the same thing.