I have seen this argument (debate) many times before and it always seems to come down to one important fact. How did you first learn kata? If you learn from someone who just has you practice over and over and over with no hands one things or pulling the moves out of the kata and playing around with them other than to JUST block/punch than I would agree that they are not good and you would be better trained learning hands on things.
BUT!!! If you learn kata and think of them as a guideline for strategy or think "what ifs" with the moves you can come up with a lot of different applications and then the kata becomes a reminder that sparks your memory of what lessons can be learned from it.
For example: Probably one of the first things many students learn is retracting your hand to the hip and performing a middle block. That's pretty basic. Now if you think differently about it and have a hand grabbing your opponent and you are pulling that to your hip and using the middle block to strike above the opponents elbow you can use the move to perform a straight armbar takedown (PPCT).
In the above scenario that is considered a "secret technique". I realize you may be thinking, "Well, everyone knows that it's not a secret". That's true now that you've had training and with the advent of such free sharing , many people know that. But, if you had no training you wouldn't know that, or when it was first taught students wouldn't have known that either. I think the word "secret" is misused alot to market things. Think of it more as "hidden" it's there in plain sight but you have to look deeper to find it.
"Hard won, buy easy lost. True karate does not stay where it is not being used."