Here’s what happens when you take an overly rigid view of Kata and application:
I have very mixed feelings about the Toguchi Seikichi’s application sets for the classical Goju-ryu kata. Although I respect the thought and effort that went into them, I feel they over-emphasize linear movement, and denature the kata.
I think there are a couple of good applications, but in general they over-emphasize linear motion and a block/response paradigm that is not effective in a real situation, or at the core of Goju-ryu tactics. Interestingly the classical kata applications mirror almost exactly the kiso-kumite template that Toguchi developed for his new kata. I think the main benefit of sets like these is that with they are easy to work with in large groups of students, and provide a basic level of technique, power, and contact in a controlled setting.
IMHO I think that sanchin is the key stone to understanding the fundamental kata of Nahate: Sesan, Sanseru, and Pechruin/Suparempei. If Sanchin kata is taught in a progressive manner from basic stepping, breath, striking and posture, and then to introducing critical principles of footwork, releases, entangling, locking and throwing, then there is little need for sets like Toguchi’s. Honestly, they miss the point entirely.