So very true. I've had my share of teachers who had no idea what the kata was all about. "Its done this way, well........because thats the way its done." was an asnwer I heard way too many times. Fortunately, I found people who could explain and give more detail.
Indeed... there's a story that floats around the 'net that makes the same point:
A young Jewish mother is preparing a brisket one Friday for Shabbat dinner. Her daughter watches with interest as the mother slices off the ends of the brisket before placing it in the roasting pan. The young girl asks her mother why she does this.
The mother pauses for a moment and then says, "You know, I'm not sure. This is the way I always saw my mother make a brisket. Let's call Grandma and ask her."
So, she phones her mother and asks why she always sliced the ends off the brisket before roasting.
The Grandmother thinks for a moment and then says, "You know, I'm not sure why. This is the way I always saw MY mother make a brisket."
Now the two women are very curious, so they pay a visit to the great-grandmother in the nursing home.
"You know when we make a brisket," they explain, "we always slice off the ends before roasting. Why is that?"
"I don't know why YOU do it," says the old woman, "but I never had a pan that was large enough."
You have to be willing to find out why and what and how - some people have instructors who, like the mother in the above story, did it that way because that the way they learned it, by rote, without explanation... and only after someone went back to the beginning and asked why something was done a particular way did they know that no one knew. The mystique in many arts prevents students from asking that key question "why", and also allows instructors to fall back on "because I said so" and/or "because that's the way I was taught".
Patterns/forms/kata/whatever you want to call it is a toolbox - the techniques contained within the patterns are tools that can be used in a wide variety of ways. You have to be willing to experiment with them, to use them in step sparring and free sparring, and make them your own. Too often people stick with the few techniques they know well, and that they know work for them, and never go beyond that point... leaving them predictable as fighters, a mistake that can be costly in the ring and deadly in self-defense.
Here's an exercise that addresses that: take a movement from a pattern, any movement, one that you don't usually use, and use it in step sparring. Use it free sparring. Play with it, modify it, make it your own. If you can't do that, then patterns are useless to you except as conditioning. If you can do it, however, you have an endless supply of techniques that you can modify to meet your needs in any situation. But you have to work for it - you can't just do the patterns and expect that, magically, the applications will come.